UBHATCr 

UNIVERSITY  OF  CALIFORNIA 
DAVIS 


/ 


ir3 


Digitized  by  the  Internet  Archive 

in  2007  with  funding  from 

IVIicrosoft  Corporation 


http://www.archive.org/details/farmmotorsstgasOOpottrich 


AGRICULTURAL    ENGINEERING    SERIE;S 
E.  B.  McCORMICK,  Consulting  Editor 


FARM   MOTORS 


^iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii        iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii 

McGraw-Hill  BookCoittpai^ 

PujStisAers  of3oo£§/br 

ElGCtrical  World         TheEngiriGGiing  and  Mining  Journal 

Mt  tnsirieGring  Record  Engineering  Nows 

Railway  Age  G  aze  tte  -^  -^  ^3  American  Machinist 

Signal  £ngirLGGr>S  -B  American Engjneei- 

j4i/El^tric  Uailway  Journal  Coal  Age  ^ 

j^Hetallurgical  and  Chemical  Engineering  P  o  we r 


5 


3-T'-<»-^ 


FARM    MOTORS 

STEAM  AND  GAS  ENGINES 

HYDRAULIC  AND  ELECTRIC  MOTORS 

WINDMILLS 


BY 

ANDREY  A.  POTTER 

MEMBER   AMERICAN   SOCIETY   OF   MECHANICAL   ENGINEERS,   PROFESSOR 
OF   STEAM   AND    GAS   ENGINEERING  IN   THE   KANSAS 
STATE   AGRICULTURAL   COLLEGE 


McGRAW-HILL  BOOK  COMPANY,  Inc. 
239  WEST  39TH  STREET,  NEW  YORK 

6  BOUVERIE  STREET,  LONDON,  E.  C. 

1913 

LTBT^ARY 

UNIVERSITY  OF  CALIFORNIA 
DAVIS 


Copyright,  1913,  by  the 
McGraw-Hill  Book  Company,  Inc. 


THE. MAPLE. PRESS. YORK. PA 


PREFACE 

In  preparing  this  book  it  has  been  the  intention  to  include  the 
fundamental  principles  governing  the  construction,  working  and 
management  of  motors  which  are  suitable  for  farm  use.  The 
motors  treated  include  steam  engines,  gas  and  oil  engines,  trac- 
tion engines,  automobiles,  water  motors,  windmills  and  electric 
motors. 

The  method  followed  in  each  chapter  was  to  give: 

1 .  the  fundamental  principles  underlying  the  particular  motor, 

2.  the  principal  parts  of  the  motor, 

3.  auxiliary  parts, 

4.  uses  to  which  the  particular  type  of  motor  is  adapted, 

5.  selection,  erection  and  management  of  the  different  machines. 
While  this  book  was  prepared  primarily  as  a  text-book  for 

students  in  agricultural  engineering,  the  subject  matter  is  so 
presented  that  it  will  be  of  equal  value  to  farmers  and  to  operators 
of  various  kinds  of  engines  and  motors.  Much  practical  informa- 
tion is  included  regarding  steam,  gas  and  electricity,  and  the  text 
is  illustrated  with  over  275  cuts. 

Some  space  is  devoted  to  the  more  refined  methods  used  in 
engineering  practice  for  improving  the  economy  of  various 
motors.  While  many  of  these  methods  are  not  used  at  the  pres- 
ent time  in  connection  with  farm  motors,  it  is  the  opinion  of  the 
author  that  a  knowledge  of  the  best  engineering  practice  is  not 
only  of  considerable  educational  value,  but  will  lead  to  the  more 
perfect  manipulation  of  the  simple  farm  motors. 

The  successful  rural  engineer  of  the  near  future  will  be  the 
man  that  applies  proven  engineering  to  the  machinery  and  con- 
structions used  on  the  farm. 

The  author  is  particularly  indebted  in  the  preparation  of  this 
book  to  Professors  E.  B.  McCormick,  M.  R.  Bowerman,  R.  A. 
Seaton,  and  W.  W.  Carlson,  of  the  Kansas  State  Agricultural 
College;  to  Professors  Allen  <^  Bursley  of  the  University  of 
Michigan;  and  to  Mr.  S.  Yesner  of  Boston,  Mass. 

A.  A.  Potter. 

Manhattan,  Kansas, 
November,  1913. 


CONTENTS 

Page 
Preface v 

CHAPTER  I 

Farm  Motors  in  General 1 

Sources  of  energy — Principles  governing  the  action  of  various 
motors — Comparison  of  various  types  of  motors. 

CHAPTER  II 

Fundamental  Principles  and  Definitions 4 

Matter — States  of  matter — Motion — Force  and  Pressure — Work — 
Energy  and  power — Horse-power — Indicated  horse-power — Brake 
horse-power — Nature  of  heat — Temperature — Thermometers — 
Units  of  heat — Mechanical  equivalent  of  heat — Specific  heat — 
Specific  gravity  Problems. 

CHAPTER  III 

Steam,  Fuel  and  Combustion 14 

Theory  of  steam  generation — Fuels.  Comparison  of  various 
fuels  available — Combustion.  Commercial  value  of  fuels — Prob- 
lems. 

CHAPTER  IV 

Steam  Boilers  and  Auxiliaries 25 

Principal  parts  of  a  steam  power  plant — Classification  of  boilers — 
Return  tubular  boiler — Internally  fired  boiler — Vertical  Fire-tube 
boilers — Water  tube  boilers — Grates  for  boiler  furnaces — Piping 
for  boilers — Pipe  fittings — Valves — Safety  valves — Steam  gages — 
Water  glass  and  gage  cocks — Water  column — Steam  traps — Feed 
pumps  and  injectors — Feed  water  heaters — Chimney  and  artificial 
draft  producing  apparatus — Firing — Mechanical  stokers — Rating  of 
boilers — Management  of  boilers. 

CHAPTER  V 

Stationary  Steam   Engines 57 

Description  of  the  steam  engine — Action  of  the  plain  slide  valve — 
Types  of  steam  engines — Valve  setting — Steam  engine  indicator 
cards — Classification  of  steam  engines — Adaptability  of  various 
types  of  steam  engines — Condensing  and  non-condensing  engines — 

vii 


viii  CONTENTS 

Page 
Losses     in     steam     engines — Steam     engine     governors — Engine 
details — ^Engine      auxiliaries — ^Lubricators — Steam      separators — 
Exhaust  pipe  heads — Condensers — Steam  turbines — Installation 
and  care  of  steam  engines. 

CHAPTER  VI 

Gas  and  Oil  Engines 93 

The  internal  combustion  engine — The  gas  engine  cycle — Classifica- 
tion of  gas  engines — The  four-stroke  cycle — The  two-stroke  cycle — 
Comparison  of  two-stroke  and  four-stroke  cycle  gas  engines — 
Gas  engine  fuels — Gasoline  and  other  distillates  of  crude  petroleum 
— Alcohol  as  a  fuel  for  gas  engine  use — Essential  parts  of  a  gas 
engine — Carbureters  for  gasoline  engines — Carbureting  kerosene 
and  the  heavier  fuels — Cooling  of  gas  engine  cylinder  walls — 
Gas  engine  ignition  systems — Automatic  ignition  for  oil  engines — 
Governing  of  gas  engines — The  gasoline  engine  on  the  farm — 
Selection  and  management  of  gas  and  oil  engines — Selecting  a  gas 
engine — Installation  of  gas  engines — Instructions  for  starting  gas 
engines — Causes  of  gas  engines  failing  to  start — Causes  of  motor 
failing  to  run — Running  a  gas  engines.  ^ 

CHAPTER  VII 

Traction  Engines  and  Automobiles      140 

Traction  engines— Fundamental  parts  of  a  traction  engine — 
Steam  traction  engines — Differentials  for  traction  engines — Gas 
traction  engines — Uses  of  traction  engines — Rating  of  traction 
engines — Management  of  traction  engines — Types  of  automobiles 
— Gasoline  automobiles — Automobile  troubles  and  remedies — 
Gasoline  motor  cycles. 

CHAPTER  VIII 

Water  Motors 171 

Determining  the  power  of  streams — Types  of  water  motors — 
Overshot,  undershot  and  breast  wheels — Impulse  water  motors — 
Water  turbines.     The  hydraulic  ram. 

CHAPTER  IX 

Windmills 184 

Types  of  windmills — Principal  parts  of  a  wind  mill — The  wind- 
wheel — The  rudder  or  vane — The  governor — Windmill  gearing — 
Windmill  brake — Towers — Method  of  erecting  windmills — Care 
of  windmills — Power  of  windmills — Uses  of  windmills. 


CONTENTS  IX 

Page 
CHAPTER  X 

Electric  Motors,  Dynamos  and  Batteries 200 

Action  of  electricity — Units  of  electricity — Ohm's  law — Wires  for 
conductors  of  electricity — Electrical  batteries — Primary  batteries 
— Storage  batteries — Methods  of  connecting  batteries — The 
electric  dynamo — Action  of  the  dynamo — Direct  and  alternating 
currents — Principal  parts  of  dynamos  and  motors — Series  wound 
dynamos — Series  wound  motors — Shunt  wound  dynamos — Shunt 
wound  motors — Compound  wound  dynamos — Compound  wound 
motors — Various  types  of  motors  compared — Distribution  of 
electric  current — Electric  meters — Fuses  and  circuit  breakers — ■ 
Switches  and  rheostats — Method  of  connecting  motors — The 
electric  motor  on  the  farm — The  farm  electric  light  plant — In- 
stallation of  electric  motors  and  dynamos — Starting  and  stopping 
motors — Starting  and  stopping  dynamos — Care  of  motors  and 
dynamos — Problems. 

CHAPTER  XI 

Mechanical  Transmission  of  Power 238 

Belts — ^Leather  belts — Rubber  belts — Canvas  belts — Care  of  belts 
— Method  of  lacing  belts — Pulleys — Method  of  calculating  sizes 
of  pulleys — Quarter  turn  belt — Chain  drives — Rope  transmission — 
Friction  gearing — Toothed  gearing — Shafting. 

Index 255 


FARM  MOTORS 


CHAPTER  I 
FARM  MOTORS  IN  GENERAL 

A  motor  is  an  apparatus  capable  of  doing  work.  Not  consid- 
ering animal  motors,  which  include  men,  horses  and  other  animals, 
the  mechanical  motors  available  for  farm  use  are :  heat  engines, 
including  steam,  gas  or  oil,  hot-air  and  solar  engines;  pressure 
engines  such  as  water  wheels  and  water  motors;  wind-mills; 
electric  motors. 

Sources  of  Energy. — The  principal  source  of  all  energy  are 
the  rays  of  the  sun.  They  causes  the  growth  of  plants  which  fur- 
nish food  and  feed  for  man  and  animals.  The  great  coal  deposits 
are  only  the  result  of  the  storing  up  of  the  sun's  rays  in  plants 
in  by-gone  days.  These  rays  are  also  responsible  for  the  raising 
of  water  from  sea  level  to  mountain  top,  thus  giving  it  energy 
which  can  be  utilized  to  turn  water  wheels  and  made  to  do  use- 
ful work. 

On  the  other  hand,  while  the  sun's  rays  are  the  fundamental 
sourse  of  all  energy  they  can  be  utilized  directly  by  man  only 
to  a  very  limited  extent.  The  secondary  sources  of  energy  are 
the  wind,  waterfalls,  carbon  in  different  forms,  such  as  coal,  pe- 
troleum or  gas,  and  chemicals  used  in  electric  batteries. 

Principles  Governing  the  Action  of  Various  Motors. — All 
motors  do  work  by  virtue  of  motion  given  to  a  piston,  blades  on 
a  wheel  or  to  an  armature  by  some  substance  such  as  water, 
steam,  gas,  air  or  electricity.  The  first  requirement  is  that  the 
above-mentioned  substance,  often  called  the  working  substance, 
be  under  considerable  pressure. 

This  pressure  in  the  case  of  the  water  motor  or  water  wheel 
is  obtained  by  collecting  water  in  dams  and  tanks,  or  by  utiHzing 
the  kinetic  energy  of  natural  water-falls.  The  total  power 
available  in  water  when  in  motion  depends  on  the  weight  of  water 
discharged  in  a  given  time,  and  on  the  head  or  distance  through 

1 


2  FARM  MOTORS 

which  the  water  is  allowed  to  fall.  The  head  of  water  can  be 
utilized  by  its  weight  or  pressure  acting  directly  on  a  piston  or 
on  blades  or  paddles  on  wheels. 

Considering  next  the  various  forms  of  heat  engines,  work  is 
accomplished  by  steam  or  gas  under  pressure,  this  pressure  being 
obtained  by  utilizing  the  heat  of  some  fuel  or  of  the  rays  of  the 
sun. 

A  motor  utilizing  the  heat  of  the  sun  is  called  a  solar  motor 
or  a  solar  engine.  The  action  of  this  type  of  motor  depends  on 
the  vaporization  of  water  into  steam  by  means  of  the  rays  of 
the  sun,  which  are  concentrated  and  intensified  by  means  of 
reflecting  surfaces. 

In  the  case  of  the  steam  engine  a  fuel  like  coal,  oil  or  gas  is 
burned  in  a  furnace  and  its  heat  of  combustion  is  utilized  in 
changing  water  into  steam,  at  high  pressure,  in  a  special  vessel 
called  a  boiler.  This  high-pressure  steam  is  then  conveyed  by 
pipes  to  the  engine  cylinder  where  its  energy  is  expended  in 
pushing  a  piston  as  in  the  case  of  the  reciprocating  engine.  The 
sliding  motion  of  the  piston  may  be  changed  into  rotary  motion 
at  the  shaft  by  the  interposition  of  a  connecting  rod  and  crank. 
Another  method  is  to  allow  the  high-pressure  steam  to  escape 
through  a  nozzle,  strike  blades  on  a  wheel  and  produce  rotary 
motion  direct,  as  in  the  case  of  the  steam  turbine. 

In  another  type  of  heat  engine,  called  a  hot-air  engine,  air  is 
heated  in  a  cyUnder  by  a  fuel  which  is  burned  outside  of  the  en- 
gine cylinder,  and  by  its  expansion  drives  a  piston  and  thus 
does  work. 

In  the  case  of  gas  and  oil  engines  the  fuel,  which  must  be  in  a 
gaseous  form  as  it  enters  the  engine  cyHnder,  is  mixed  with  air 
in  the  proper  proportions  to  form  an  explosive  mixture.  It  is 
then  compressed  and  ignited  within  the  cylinder  of  the  engine, 
the  high  pressures  produced  by  the  explosion  pushing  on  a  piston 
and  doing  work.  These  engines  belong  to  a  class  called  internal- 
combustion  engines,  and  differ  from  the  steam  and  hot-air 
engines,  which  are  sometimes  called  external-combustion  en- 
gines, in  that  the  fuel  with  air  is  burned  inside  the  engine  cyHnder, 
instead  of  in  an  auxiUary  apparatus. 

The  wind-mill  derives  its  high  pressure  for  doing  work  from  the 
moving  atmosphere. 


FARM  MOTORS  IN  GENERAL  3 

The  electric  motor  converts  electrical  energy  at  high  pressnre- 
into  work;  this  electrical  pressure  or  voltage  being  produced 
in  an  apparatus  called  an  electrical  dynamo,  or  generator. 

Comparison  of  Various  Types  of  Motors. — The  solar  motor 
is  but  Httle  used  on  account  of  its  high  first  cost  and  great  bulk 
in  relation  to  the  small  power  developed. 

In  localities  where  the  wind  is  abundant  and  little  power  is 
needed,  the  wind-mill  is  the  most  desirable  and  cheapest  power. 
The  greatest  appHcation  of  wind-mills  is  for  the  pumping  of  water 
for  residences  and  farms,  and  for  such  other  work  as  does  not 
suffer  from  suspension  during  calm  weather.  Electric  storage  and 
lighting  on  a  small  scale  from  the  power  of  a  wind-mill  has  been 
tried  in  several  places  with  fair  success,  but  will  probably  not  be 
adapted  to  any  great  extent  on  account  of  the  high  first  cost  of 
such  an  installation. 

The  water  motor  or  water  turbine  is  very  economical  if  a 
plentiful  supply  of  water  can  be  had  at  a  fairly  high  head,  but  its 
reliability  is  affected  by  drought,  floods  and  ice  in  the  water 
supply. 

The  hot-air  engine,  while  not  economical  in  fuel  consumption,  is 
well  adapted  for  pumping  water  in  places  where  the  cost  of  fuel 
is  not  an  important  item  and  where  safety  and  simplicity  of  mech- 
anism are  essential. 

Of  the  other  forms  of  heat  engines,  the  internal  combustion 
engine,  whether  using  gas  or  oil,  is  well  adapted  for  small  and 
medium  size  powers,  such  as  for  farm  use  and  irrigation  work. 

For  the  generation  of  electricity  and  in  large  sizes  the  steam 
engine  or  steam  turbine  will  be  found  more  suitable  on  account  of 
their  lower  first  cost  and  greater  rehability. 

If  a  source  of  electric  current  is  available  at  a  low  price,  the 
electric  motor  is  very  desirable,  as  it  requires  little  care  and  can 
be  bought  in  sizes  to  suit  all  requirements. 


CHAPTER  II 
•      FUNDAMENTAL  PRINCIPLES  AND  DEFINITIONS 

Before  a  study  is  made  of  any  motor,  the  fundamental  concep- 
tions of  physics  regarding  states  of  matter,  work,  power  and  heat 
are  essential. 

Matter. — Matter  is  that  which  occupies  space  and,  when  Hm- 
ited  in  amount,  it  is  called  a  body.  Matter  in  any  form  consists 
of  a  great  many  small  particles,  called  molecules,  the  relative 
position  of  which  determines  the  state  in  which  a  substance 
exists. 

States  of  Matter. — Matter  exists  in  the  soHd,  liquid  and  gaseous 
states. 

In  the  case  of  the  solid  the  relative  positions  of  the  molecules  are 
fixed.  A  solid  having  a  certain  shape  or  form,  whether  due  to 
natural  or  artificial  causes,  will  retain  that  form,  unless  and  until 
it  is  made  to  change  same  by  some  external  cause. 

In  the  case  of  the  liquid,  the  relative  position  of  the  various 
molecules  is  not  fixed.  The  shape  or  form  of  a  Uquid  depends, 
therefore,  on  the  soHd  walls  surrounding  it,  a  liquid  assuming  the 
form  of  any  vessel  in  which  it  may  be  placed. 

In  the  case  of  a  gas  the  various  molecules  struggle  to  occupy 
greater  space.  A  gas  can  be  greatly  compressed  by  an  external 
force,  and  will  expand  to  an  unlimited  extent,  if  it  is  given  perfect 
freedom. 

Motion. — Motion  means  change  of  place.  If  a  definite  amount 
of  matter,  called  a  body,  is  removed  from  one  place  to  another, 
motion  is  produced. 

Force  and  Pressure. — Anything  which  produces  or  tends  to 
produce,  modifies  or  tends  to  modify  motion  is  called  force. 
Force  is  measured  in  pounds.  Pressure  is  the  intensity  of  force 
and  is  equal  to  the  total  force  divided  by  the  area  over  which  it 
acts.  For  example  a  force  of  1000  lb.  acting  on  a  body  whose 
dimensions  are  5  in.  by  2  in.,  will  produce  a  pressure  or  intensity 
of  force  equal  to  the  force  divided  by  the  area  of  the  body  in 

4 


FUNDAMENTAL  PRINCIPLES  AND  DEFINITIONS      5 

square  inches,  or  -fj- =100  lb.  In  English  and  American^rac-, 
tice,  pressure  is  always  expressed  in  pounds  per  square  inch. 
Thus  when  a  steam  gage  on  a  boiler  is  registering  80  lb.,  this  means 
that  the  steam  is  capable  of  transmitting  a  force  of  80  lb.  for  every 
square  inch  on  which  it  acts.  If  it  is  allowed  to  act  on  a  12-in. 
piston,  the  area  of  which  is  113  sq.  in.,  the  total  force  exerted  on 
the  piston  is  80  times  113,  or  9040  lb. 

The  pressure  exerted  by  the  atmosphere  is  called  barometric 
pressure.  The  barometric  pressure  is  14.7  lb.  per  square  inch  at 
sea  level  and  decreases  as  the  altitude,  or  the  height  of  the  surface 
of  the  earth  above  sea  level,  increases.  For  each  2000  ft.  in 
elevation  the  pressure  of  the  atmosphere  is  decreased  by  about 
lib. 

Work,  Energy  and  Power. — Work  means  force  times  distance 
through  which  it  acts  and  is  independent  of  time.  If  a  body  of 
1  lb.  is  raised  through  a  distance  of  1  ft.,  the  resulting  work  is 
1  ft.-lb. 

The  capacity  for  doing  work  is  called  energy.  Energy  existing 
in  a  body  at  rest,  as  in  the  case  of  the  raised  weight,  is  called  poten- 
tial energy.  Energy  possessed  by  a  body  when  in  motion  is 
called  kinetic  energy. 

As  an  illustration,  a  cubic  foot  of  water,  weighing  62.5  lb. 
when  at  rest  at  a  height  of  100  ft.,  has  potential  energy  of  6250 
ft.-lb.  and  this  potential  energy  is  changed  into  kinetic  energy 
of  work  when  the  water  is  allowed  to  fall  through  that  height. 
The  water  in  the  above  example  when  allowed  to  fall  through  10 
ft.  will  be  capable,  on  account  of  its  kinetic  energy,  to  do  625  ft.- 
lb.  of  work  and  will  have  a  potential  energy  of  6250  —  625, 
or  5625  ft.-lb.  when  it  comes  again  to  rest. 

Power  takes  into  consideration  the  time  it  takes  to  do  a 
certain  amount  of  work  and  is  defined  as  the  rate  of  doing  work. 
Thus  if  steam  at  a  pressure  of  100  lb.  moves  a  piston  18  in.  in 
diameter  through  a  distance  of  2  ft.,  the  work  done  is  100  times 
254.46  (the  area  of  the  piston  in  inches  multiplied  by  the  distance 
in  feet)  or  25,446  ft.-lb.  The  power  of  the  engine,  however, 
depends  on  the  time  that  the  steam  requires  to  move  the  piston 
through  the  given  distance  and,  if  the  motion  is  accomplished 
in  one  second,  the  power  of  the  engine  is  five  times  greater  than 
if  five  seconds  were  required. 


6 


FARM  MOTORS 


Horse-power. — If  work  is  done  at  the  rate  of  33,000  ft. -lb. 
per  minute,  1  h.p.  is  said  to  be  exerted.  This  means  that  an 
engine  will  have  a  capacity  of  1  h.p.  if  it  can  do  550  ft. -lb.  of 
work  in  a  second,  33,000  ft. -lb.  of  work  in  a  minute  or  1,980,000 
ft.-lb.  of  work  in  an  hour.  In  the  example  of  the  previous  para- 
graph if  the  piston  passes  through  the  distance  of  2  ft.  in  one- 
fiftieth  of  a  minute,  the  power  of  the  engine  in  horse-power  is 
25,546X2 


33,000  x5V 


77.4 


Fig.  1. 


It  is  important  to  remember  that  power  takes  into  considera- 
tion work  and  time.  All  animals,  including  man,  are  able  to 
produce  more  power  for  a  short  period  of  time,  while  mechanical 
motors,  whether  driven  by  water,  wind,  steam,  gas  or  electricity 
can  exert,  with  proper  care,  the  power  for  which  they  are  designed 
for  an  indefinite  length  of  time. 

Indicated  Horse-power. — The  term  indicated  horse-power 
(i.h.p.)  is  appHed  to  the  rate  of  doing  work  by  steam  or  by  a  gas  in 


FUNDAMENTAL  PRINCIPLES  AND  DEFINITIONS      7 

the  cylinder  of  an  engine,  and  is  obtained  by  means  of  a  special, 
instrument,  called  an  indicator.  One  form  of  this  type  of  in- 
strument, the  Crosby,  is  shown  in  section  in  Fig.  1.  It  consists 
essentially  of  a  cylinder  4,  which  is  placed  in  direct  communica- 
tion with  the  engine  cylinder,  and  in  which  moves  a  piston  8  com- 
pressing a  spring  above  it  and  raising  the  arm  16.  At  the  end  of 
the  arm  is  a  pencil  23  which  records  graphically  the  pressure  of 
the  steam  in  the  engine  cylinder  on  the  revolving  drum  24.  This 
drum  24  is  covered  with  paper  and  receives  its  motion  from  the 
engine  cross-head.  From  the  diagram  drawn  on  the  drum  of  the 
indicator,  the  average  pressure  is  determined,  and  the  horse-power 
is  calculated  from  this  and  from  dimensions  and  speed  of  the 
engine. 

As  an  illustration,  if  the  average  unbalanced  pressure  of  the 
steam  on  the  piston,  as  obtained  by  means  of  an  indicator,  and 
called  the  mean  effective  pressure,  is  40  lb.  for  a  12-in.  X  13-in. 
steam  engine  running  at  250  r.p.m.,  the  total  pressure  exerted 
by  the  steam  on  a  12-in.  piston  is 

40X113.1=4524  lb. 

Since  the  stroke  is  13  in.,  the  work  done  in  one  end  in  foot- 
pounds per  revolution  is 

1Q 

4524  Xj|  =  4901 

The  engine  making  250  r.p.m.,  the  work  per  minute  will  be 

4901X250  =  1,225,250  ft.-lb. 

Since  33,000  ft.-lb.  per  minute  is  1  h.p.,  the  power  of  the  engine  is: 
1,225,250 


33,000 


=  37.1i.h.p. 


As  steam  engines  are  usually  double  acting,  an  indicator  card 
would  have  to  be  taken  of  the  crank  end,  the  mean  effective 
pressure  determined  for  that  end  and  the  indicated  horse-power 
calculated  by  the  above  method,  taking  into  consideration  the 
size  of  the  piston  rod.  The  total  indicated  horse-power  of  the 
engine  is  the  sum  of  that  calculated  for  the  two  ends. 

Brake  Horse -power. — Brake  horse-power  represents  the  ac- 
tual power  which  a  motor  or  engine  can  deliver  for  the  purpose 


8 


FARM  MOTORS 


of  work  at  a  shaft  or  a  brake .  An  instrument  for  the  measurement 
of  the  brake  horse-power  of  motors,  and  called  a  Prony  Brake, 
is  shown  in  Fig.  2.  It  consists  of  two  wooden  blocks  BB  which 
fit  around  the  pulley  P  and  are  tightened  by  means  of  the  thumb 
nuts  NN.  A  projection  of  one  of  the  blocks,  the  lever  L,  rests 
on  the  platform  scales  S.  When  the  brake  is  balanced,  the  power 
absorbed  is  measured  by  the  weight  as  registered  on  the  scales 
multiplied  by  the  distance  it  would  pass  through  in  that  time 
if  free  to  move.  If  1  is  the  length  of  the  brake  arm  in  feet,  w  the 
weight  as  registered  on  the  scales  in  pounds  and  n  the  revolutions 
per  minute  of  the  motor,  the  horse-power  absorbed  can  be  calcu- 
lated by  the  formula 


Brake  horse-power  = 


2;rlwn 

spoo 


umnnmmmmmmnmmmm 


Fig.  2. 


As  an  illustration,  the  scale  reading  of  an  engine  running  at  250 
r.p.m.  is  80  lb.  If  the  length  of  the  brake  arm  is  SJ  ft.,  calcu- 
late the  brake  horse-power  developed. 


Brake  horse-power  = 


2X3.1416X5.25X80X250 
33,000 


19.04 


Nature  of  Heat. — Heat  is  a  form  of  energy  and  not  a  material 
substance.  The  heat  of  a  body  depends  on  the  vibratory  motion 
of  the  particles  or  molecules  of  which  the  body  is  built  up,  the 
greater  the  rate  of  motion  of  these  molecules  the  higher  is  the 
temperature  of  the  body. 


FUNDAMENTAL  PRINCIPLES  AND  DEFINITIONS      9 

Temperature. — Temperature  indicates  the  relative  heats  of 
bodies,  or  the  relative  rate  of  motion  of  the  molecules  in  bodies.' 
Temperature  is  not  a  measure  of  the  amount  or  quantity  of 
heat  in  a  body.  Thus  a  small  and  a  large  piece  of  metal  may 
be  heated  to  the  same  temperature,  but  the  large  piece  would 
possess  the  greater  quantity  of  heat.  Temperature  is  an  indica- 
tion of  the  sensible  heat  of  a  substance,  or  the  heat  intensity 
which  can  be  revealed  to  the  senses  of  an  observer. 

Thermometers. — A  thermometer  is  an  instrument  by  means  of 
which  the  temperature  of  a  substance  is  measured.  As  usually 
constructed,  it  consists  of  a  liquid  such  as  mercury  or  alcohol 
enclosed  in  a  bulb  at  one  end  of  a  thin  glass  tube,  the  temperature 
changes  producing  sufficient  variations  in  the  expansion  of  the 
Hquid  as  can  be  read  off  on  a  scale  attached  to,  or  graduated,  on 
the  glass  tube. 

Thermometers  are  graduated  in  three  different  ways,  which  are 
called  the  three  thermometric  scales,  the  type  of  scale  depending 
on  the  number  of  graduations,  or  degrees  (°  denotes  degree) 
between  the  melting-point  of  ice  and  the  boiling-point  of  water. 

The  scale  mostly  used  in  EngHsh-speaking  countries  is  the 
Fahrenheit  (F.).  In  this  case  the  melting-point  of  ice  is  taken  at 
32°  and  the  boiling-point  of  water  at  212°.  Thus  the  Fahrenheit 
degree  (°  F.)  is  1/180  of  the  interval  between  the  two  fixed  points. 

In  scientific  work  the  Centigrade  scale  is  used  in  most  coun- 
tries. The  centigrade  degree  is  1/100  of  the  temperature  inter- 
val between  the  melting-point  of  ice  and  the  boiling-point  of 
water,  these  two  fixed  points  being  denoted  0°  C.  and  100°  C. 
respectively. 

Another  scale,  used  only  to  a  limited  extent  in  certain  countries 
of  Europe  is  the  Reaumur  scale  which  has  the  melting-point  of 
ice  at  0°  R.  and  the  boiling-point  of  water  at  80°  R. 

The  relations  existing  between  the  thermometric  scales  mostly 
used,  i.e.,  the  Fahrenheit  (F.)  and  the  Centigrade  (C.)  can  be 
expressed : 

degrees  C.  =  5/9  (degrees  F.  — 32) 
degrees  F.  =  9/5  degrees  C.+32 

Example:  Convert  15°  C.  to  the  Fahrenheit  scale  and  400° 
F.  to  the  Centigrade  scale. 


10 


FARM  MOTORS 


degrees  F.  =  9/5 X degrees  C.+32 
=  9/5X15+32 
=  27+32  =  59°  F. 
degrees  C.  =  5/9  (degrees  F.  — 32) 
=  5/9  (400-32) 
=  204°  C. 
Table  1  can  be  used  for  converting  Centigrade  into  Fahrenheit 
degrees  and  conversely. 

TABLE     1.— RELATION    BETWEEN     THE    FAHRENHEIT    AND 
CENTIGRADE  THERMOMETRIC  SCALES 


Fahr. 

Cent. 

Fahr. 

Cent. 

-30 

-34.4 

210 

98.9 

-20 

-28.9 

212 

100.0 

-10 

-23.3 

220 

104.4 

0 

-17.8 

230 

110.0 

+10 

-12.2 

240 

119.6 

20 

-  6.7 

250 

121.1 

30 

-  1.1 

260 

126.7 

32 

0.0 

270 

132.2 

40 

+  4.4 

280 

137.8 

50 

10.0 

290 

143.3 

60 

15.6 

300 

148.9 

70 

21.1 

310 

154.4 

80 

26.7 

320 

160.0 

90 

32.2 

330 

165.6 

100 

37.8 

340 

171.1 

110 

43.3 

350 

176.7 

120 

48.9 

360 

182.2 

130 

54.4 

370 

187.8 

140 

60.0 

380 

193.3 

160 

65.6 

390 

198.9 

160 

71.1 

400 

204.4 

170 

76.7 

410 

210.0 

180 

82.2 

420 

215.6 

190 

87.8 

430 

221.1 

200 

93.3 

440 

226.7 

Units  of  Heat. — Heat  is  measured  in  heat  units.  A  heat  unit 
is  the  amount  of  heat  required  to  raise  the  temperature  of  one 
pound  of  water  one  degree.  The  heat  unit  used  in  English 
speaking  countries  is  the  British  Thermal  Unit  (B.t.u.).  The 
B.t.u.  is  defined  as  the  amount  of  heat  required  to  raise  one  pound 
of  water  from  62°  F.  to  63°  F. 


FUNDAMENTAL  PRINCIPLES  AND  DEFINITIONS     11 


When  a  certain  illuminating  gas  is  said  to  contain  600  B.t.tu, 
this  means  that  each  cubic  foot  of  the  gas  is  capable  of  raising 
the  temperature  of  10  lb.  of  water  through  60°  F.,  or  that  it  will 
raise  the  temperature  of  water  so  that  the  product  of  the  weight  of 
water  and  temperature  rise  (in  °  F.)  is  600. 

Mechanical  Equivalent  of  Heat. — It  was  proved  experimentally 
that  heat  and  work  are  mutually  convertible.  It  requires 
778  ft.-lb.  of  work  to  produce  1  B.t.u.;  and  similarly  1  B.t.u.  will 
produce  778  ft.-lb.  of  work,  if  all  the  heat  is  converted  into  work. 
778  is  called  the  mechanical  equivalent  of  heat.  It  is  due  to  the 
fact  that  heat  can  be  converted  into  work  that  the  various  heat 
engines,  including  the  steam,  gas  and  oil  engines  are  possible. 

Specific  Heat. — As  the  addition  of  the  same  quantity  of  heat 

TABLE    2.— SPECIFIC    HEATS    AND    SPECIFIC    GRAVITIES    OF 
COMMON  SUBSTANCES 


Name  of  substance 

Specific  heat 
(average) 

Specific  gravity 
(average) 

Solids 
Iron,  cast 

0.1298 

0.1138 

0.1170 

0.0314 

0.0951 

0.170 

0.504 

0.21 

0.20 

7  21 

Iron,  wrought 

7  70 

Steel 

7  80 

Lead 

11  4 

CoDDer 

R  QO 

Glass 

2  60 

Ice 

0  90 

Stone 

2  75 

Brick  work,  masonry 

2.00 

Liquids 
Water 

1.000 
0.475 
0.535 
0.550 
0.590 

1  000 

Kerosene 

0  810 

Gasoline 

0  690 

Alcohol,  ethyl 

0  790 

Alcohol,  methyl 

0  808 

Ammonia 

0  950 

Vegetable  oil 

0.400 

0  900 

Gases 
Air 

0.2375 
0.2175 
3.4090 
0.2438 
0.508 

1  000 

Oxygen 

1  1052 

Hydrogen .    .    . 

0  0fiQ2 

Nitrogen 

0  9701 

Ammonia 

0.5889 

12  FARM  MOTORS 

will  not  produce  the  same  temperature  changes  in  equal  weights 
of  different  substances,  it  is  evident  that  the  amount  of  heat 
which  can  be  taken  in  or  given  out  by  any  substance  depends  on 
the  capacity  of  that  substance  for  heat.  The  capacity  of  a  sub- 
stance for  heat  or  the  resistance  which  a  substance  oft'ers  to  a 
change  in  its  temperature,  is  called  its  specific  heat.  The 
specific  heat  of  water  is  taken  as  the  standard  and  equal  to  one. 

Specific  Gravity. — By  specific  gravity  is  meant  the  relation 
existing  between  the  weight  of  any  substance  and  the  weight  of 
an  equal  volume  or  bulk  of  water.  Thus  the  specific  gravity 
of  cast  iron  is  about  7,  which  means  that  a  cubic  foot  of  iron 
is  seven  times  heavier  than  a  cubic  foot  of  water.  In  Table  2 
are  given  the  specific  heats  and  specific  gravities  of  common 
substances. 

PROBLEMS 

1.  Calculate  the  work  done  by  a  pump  when  lifting  100  gallons  of  water 
to  a  height  of  125  ft. 

2.  The  pressure  of  steam  on  the  piston  of  an  engine  is  30  lb.  If  the  diam- 
eter of  the  piston  is  18  in.,  its  stroke  2  ft.,  how  much  work  does  the  engine 
do  per  hour  if  its  speed  is  110  r.p.m.? 

3.  Calculate  the  horse-power  of  the  engine  in  the  above  problem. 

4.  A  mine  cage  weighing  3000  lb.  is  to  be  lifted  up  a  750-ft.  shaft  in 
1/2  minute.  Calculate  the  horse-power  of  the  motor  required,  allow- 
ing 20  per  cent,  for  losses. 

6.  Calculate  the  horse-power  of  a  traction  engine  required  to  draw  a  plow 
at  the  rate  of  2  miles  per  hour  if  the  pull  on  the  draw  bar  is  15,000  lb. 

6.  Convert  the  following  readings  in  degrees  Centigrade  to  the  Fahren- 
heit scale: 

-18,  -2,  15,53,78. 

7.  Convert  the  following  readings  on  the  Fahrenheit  scale  to  degrees 
Centigrade: 

-20,  10,  60,  80,  220,  350. 

8.  A  pound  of  gasoline  will  yield  when  completely  burned  19,200  heat 
units,  calculate  the  foot-pounds  of  energy  contained. 

9.  Calculate  the  heat  required  to  raise  the  temperatures  of  cast  iron, 
copper,  glass,  stone  and  water  through  100°  F. 

10.  Calculate  and  compare  the  weights  of  a  gallon  of  kerosene,  of  gasoUne, 
of  ethyl  alcohol,  of  ammonia  and  of  water. 

11.  Calculate  the  indicated  horse-power  of  an  engine  having  the  following 
dimensions: 


FUNDAMENTAL  PRINCIPLES  AND  DEFINITIONS    13 

Diameter  of  cylinder 16  in.  ~     " 

Diameter  of  piston  rod 2  1/2  in. 

Stroke 24  in. 

Revolutions  per  minute 120 

Mean  effective  pressure,  head  end 52 . 3 

Mean  effective  pressure,  crank  end 52 . 0 

12.  A  gasoline  engine  running  at  300  r.p.m.  is  tested  by  means  of  a 
Prony  brake.  If  the  length  of  the  brake  arm  is  42  in.  and  the  net  weight 
as  registered  on  the  platform  scales  is  35  lb.,  calculate  the  brake  horse-power 
developed  by  the  engine. 


CHAPTER  III 
STEAM,  FUELS  AND  COMBUSTION 

Theory  of  Steam  Generation. — If  heat  is  added  to  ice,  the 
effect  will  be  to  raise  its  temperature  until  the  thermometer 
indicates  32°  F.  When  this  point  is  reached,  a  further  addition 
of  heat  does  not  produce  an  increase  in  temperature  until  all 
the  ice  is  changed  into  water,  or  in  other  words  melts.  It  has 
been  found  experimentally  that  144  B.t.u.  are  required  to  change 
1  lb.  of  ice  into  water.  This  quantity  is  called  the  latent  heat 
of  liquefaction  of  ice. 

After  the  quantity  of  ice  given,  which  for  simplicity  may  be 
taken  as  1  lb.,  has  all  been  turned  into  water,  it  will  be  found  that 
if  more  heat  is  added  the  temperature  of  the  water  will  again 
increase,  though  not  as  rapidly  as  did  that  of  the  ice.  While 
the  addition  of  each  British  thermal  unit  increases  the  tempera- 
ture of  ice  2°  F.,  in  the  case  of  water  an  increase  of  only  about  1° 
will  be  noticed  for  each  British  thermal  unit  of  heat  added. 
This  difference  is  due  to  the  fact  that  the  specific  heat,  or  resist- 
ance offered  by  ice  to  a  change  in  temperature  is  one-half  that 
offered  by  water.     That  is,  the  specific  heat  of  ice  is  0.5. 

If  the  water  is  heafed  in  a  vessel  open  to  the  atmosphere,  its 
temperature  will  keep  on  going  up  until  about  212°  F.,  the  boiling- 
point  of  water,  when  further  addition  of  heat  will  not  produce 
any  temperature  changes,  but  steam  will  issue  from  the  vessel. 
It  has  been  found  that  about  970  B.t.u.  will  be  required  to  change 
a  pound  of  water  at  atmospheric  pressure  and  at  212°  F.  into 
steam.  The  quantity  of  heat  so  supplied  which  changes  the 
physical  state  of  water  from  the  liquid  state  to  steam  is  called 
the  latent  heat  of  vaporization. 

If  the  above  operations  are  performed  in  a  closed  vessel,  water 
will  boil  at  a  higher  temperature  than  212°  F.,  since  the  steam 
driven  off  cannot  escape  and  is  compressed,  raising  the  pressure 
and  consequently  the  temperature.  The  latter  is  the  condition 
in  an  ordinary  steam  boiler. 

That  the  boiling-point  of  water  depends  on  the  pressure  is 

14 


STEAM,  FUELS  AND  COMBUSTION  15 

well  known.     Thus  in  a  place  in  Colorado  where  the  altitude-is, 
6000  ft.  above  sea  level  and  the  barometric  pressure  is  12.6  lb. 
per  square  inch  the  boiling-point  of  water  is  about  204°  F.  as 
compared  with  212°  F.  at  sea  level  where  the  barometric  pressure 
is  14.7  lb.  per  square  inch. 

As  the  pressure  is  increased  to  60  lb.  per  square  inch  by  the 
gage,  it  will  be  found  that  the  boiling-point  of  water  is  275°  F. 
At  100  lb.  per  square  inch  water  will  boil  at  317°  F.  and  at  150  lb. 
the  temperature  will  read  350.5°  F.  before  steam  will  be  formed. 

Steam  is  spoken  of  as  being  in  three  conditions : 

1.  Wet. 

2.  Dry  and  saturated. 

3.  Superheated. 

In  the  first  case  the  steam  carries  with  it  a  certain  amount  of 
water  which  has  not  been  evaporated.  The  percentage  of  this 
water  determines  the  condition  of  the  steam;  that  is,  if  there  is 
3  per  cent,  by  weight  of  moisture,  the  steam  is  spoken  of  as  being 
97  per  cent.  dry.  A  stationary  boiler,  properly  erected  and  oper- 
ated and  of  suitable  size,  should  generate  steam  that  is  98  per 
cent.  dry.  If  there  is  more  than  3  per  cent,  moisture,  there  is 
every  reason  to  believe  that  the  boiler  is  improperly  installed, 
inefficiently  operated,  or  is  too  small  for  the  work  to  be  done. 

The  second  condition,  that  of  dry  and  saturated,  may  be  con- 
sidered the  standard  for  steam.  In  this  case  the  steam  carries 
with  it  no  water  that  has  not  been  evaporated,  that  is,  it  is  dry, 
and  has  a  temperature  corresponding  with  its  pressure.  Any  loss 
of  heat,  however  small,  not  accompanied  by  a  corresponding 
reduction  in  pressure,  will  cause  condensation,  and  wet  steam  will 
be  the  result.  It  is  because  of  this  property  that  this  condition 
of  the  steam  is  designated  as  saturated  as  well  as  dry. 

An  increase  in  temperature  not  accompanied  by  an  increase  in 
pressure  will  cause  the  steam  to  acquire  a  condition  that  will 
permit  a  loss  of  heat  at  constant  pressure  without  condensation 
necessarily  following.  This  third  condition  is  called  superheat. 
The  advantage  of  superheated  steam  lies  in  the  fact  that  its 
temperature  may  be  reduced  by  the  amount  of  the  superheat 
without  causing  condensation.  This  makes  it  possible  to  trans- 
mit the  steam  through  mains  and  still  have  it  dry  and  saturated 
at  the  time  it  reaches  the  engine  cylinder. 


16 


FARM  MOTORS 


The  pressure  of  steam  will  remain  constant  if  it  is  used  as  fast 
as  it  is  generated.  If  an  engine  uses  steam  too  rapidly  the  boiler 
pressure  will  drop  and  similarly  if  the  fuel  is  burned  at  a  constant 
rate  and  an  insufficient  amount  of  steam  is  used  the  pressure  of 
the  steam  in  the  boiler  will  increase. 

In  Table  3  are  given  some  of  the  most  important  properties  of 
saturated  steam  which  include: 

1.  Pressure  of  steam  in  pounds  per  square  inch  absolute. 
Temperatures  of  steam  in  degrees  Fahrenheit.  This 
column  of  temperatures  shows  the  vaporization 
temperature  at  each  of  the  given  pressures. 
Heat  of  the  liquid,  or  the  heat  required  to  bring  up  a 
pound  of  water  from  freezing-point  to  boiling-point. 
The  latent  heat,  or  the  heat  required  to  vaporize  a 
pound  of  water  at  the  given  pressure  after  boiling- 
point  is  reached. 

The  volume  of  1  lb.  of  steam  at  the  various  pressures. 
Density  of  steam  in  pounds  per  cubic  foot. 
-The  fuels  most  commonly  used  for  steam  generation 
are  coal,  wood,  petroleum  oils  and  natural  gas.  The  combus- 
tible, or  heat-producing,  constituents  of  all  fuels  are  carbon  and 
hydrogen.     A  fuel  containing  much  sulphur  should  be  avoided 


2. 


3. 


5. 
6. 
Fuels.- 


TABLE  3.— PROPERTIES  OF  SATURATED  STEAM 

English  Units 

1- 

1 

Specific 

Volume 

Cu.  Ft.  per 

Pound 

§  g  :3 

P-I 

If: 

.0886 

t 
32 

h 

0 

L 
1072.6 

H 

1072.6 

V 

3301.0 

1 
.000303 

.0886 

.2562 

60 

28.1 

1057.4 

1085.5 

1207.5 

.000828 

.2562 

.5056 

80 

48.1 

1046.6 

1094.7 

635.4 

.001573 

.5056 

1 

101.8 

69.8 

1034.6 

1104.4 

333.00 

.00300 

1 

2 

126.1 

94.1 

1021.4 

1115.5 

173.30 

.00577 

2 

3 

141.5 

109.5 

1012.3 

1121.8 

118.50 

.00845 

3 

4 

153.0 

120.9 

1005.6 

1126.5 

90.50 

.01106 

4 

5 

162.3 

130.2 

1000.2 

1130.4 

73.33 

.01364 

5 

6 

170.1 

138.0 

995.7 

1133.7 

61.89 

.01616 

6 

7 

176.8 

144.8 

991.6 

1136.4 

53.58 

.01867 

7 

8 

182.9 

150.8 

988.0 

1138.8 

47.27 

.02115 

8 

STEAM,  FUELS  AND  COMBUSTION  17 

TABLE  3.— PROPERTIES  OF  SATURATED  STEAM— Continued 
English  Units 


II-: 

1. 

1§ 
Kg 

Specific 

Volume 

Cu.  Ft.  per 

Pound 

p 

t 

h 

L 

H 

V 

I 

P 

9 

188.3 

156.3 

984.8 

1141.1 

42.36 

.02361 

9 

10 

193.2 

161.2 

981.7 

1142.9 

38.38 

.02606 

10 

11 

197.7 

165.8 

978.9 

1144.7 

35.10 

.02849 

11 

12 

202.0 

170.0 

976.3 

1146.3 

32.38 

.03089 

12 

13 

205.9 

173.9 

973.9 

1147.8 

30.04 

.03329 

13 

14 

209.6 

177.6 

971.6 

1149.2 

28.02 

.03568 

14 

14.7 

212.0 

180.1 

970.0 

1150.1 

26.79 

.03733 

14.7 

15 

213.0 

181.1 

969.4 

1150.5 

26.27 

.03806 

15 

16 

216.3 

184.5 

967.3 

1151.8 

24.77 

.04042 

16 

17 

219.4 

187.7 

965.3 

1153.0 

23.38 

.04277 

17 

18 

222.4 

190.6 

963.4 

1154.0 

22.16 

.04512 

18 

19 

225.2 

193.5 

961.5 

1155.0 

21.07 

.04746 

19 

20 

228.0 

196.2 

959.7 

1155.9 

20.08 

.04980 

20 

21 

230.6 

198.9 

958.0 

1156.9 

19.18 

.05213 

21 

22 

233.1 

201.4 

956.4 

1157.8 

18.37 

.05445 

22 

23 

235.5 

203.9 

954.8 

1158.7 

17.62 

.05676 

23 

24 

237.8 

206.2 

953.2 

1159.4 

16.93 

.05907 

24 

25 

240.1 

208.5 

951.7 

1160.2 

16.30 

.0614 

25 

26 

242.2 

210.7 

950.3 

1161.0 

15.71 

.0636 

26 

27 

244.4 

212.8 

948.9 

1161.7 

15.18 

.0659 

27 

28 

246.4 

214.9 

947.5 

1162.4 

14.67 

.0682 

28 

29 

248.4 

217.0 

946.1 

1163.1 

14.19 

.0705 

29 

30 

250.3 

218.9 

944.8 

1163.7 

13.74 

.0728 

30 

31 

252.2 

220.8 

943.5 

1164.3 

13.32 

.0751 

31 

32 

254.1 

222.7 

942.2 

1164.9 

12.93 

.0773 

32 

33 

255.8 

224.5 

941.0 

1165.5 

12.57 

.0795 

33 

34 

257.6 

226.3 

939.8 

1166.1 

12.22 

.0818 

34 

35 

259.3 

228.0 

938.6 

1166.6 

11.89 

.0841 

35 

36 

261.0 

229.7 

937.4 

1167.1 

11.58 

.0863 

36 

37 

262.6 

231.4 

936.3 

1167.7 

11.29 

.0886 

37 

38 

264.2 

233.0 

935.2 

1168.2 

11.01 

.0908 

38 

39 

265.8 

234.6 

934.1 

1168.7 

10.74 

.0931 

39 

40 

267.3 

236.2 

933.0 

1169.2 

10.49 

.0953 

40 

41 

268.7 

237.7 

931.9 

1169.6 

10.25 

.0976 

41 

42 

270.2 

239.2 

930.9 

1170.1 

10.02 

.0998 

42 

43 

271.7 

240.6 

929.9 

1170.5 

9.80 

.1020 

43 

44 

273.1 

242.1 

928.9 

1171.0 

9.59 

.1043 

44 

45 

274.5 

243.5 

927.9 

1171.4 

9.39 

.1065 

45 

46 

275.8 

244.9 

926.9 

1171.8 

9.20 

.1087 

46 

18 


FARM  MOTORS 


TABLE  3.— PROPERTIES  OF  SATURATED  STEAM- 
English  Units 


-Continued 


II 

ill 
1? 

la 

Specific 

Volume 

Cu.  Ft.  per 

Pound 

Density 

Pounds  per 

Cu.  Ft. 

p 

t 

h 

L 

H 

V 

1 

V 

V 

47 

277.2 

246.2 

926.0 

1172.2 

9.02 

.1109 

47 

48 

278.5 

247.6 

925.0 

1172.6 

8.84 

.1131 

48 

49 

279.8 

248.9 

924.1 

1173.0 

8.67 

.1153 

49 

50 

281.0 

250.2 

923.2 

1173.4 

8.51 

.1175 

50 

51 

282.3 

251.5 

922.3 

1173.8 

8.35 

.1197 

51 

52 

283.5 

252.8 

921.4 

1174.2 

8.20 

.1219 

52 

53 

284.7 

254.0 

920.5 

1174.5 

8.05 

.1241 

53 

54 

285.9 

255.2 

919.6 

1174.8 

7.91 

.1263 

54 

55 

287.1 

256.4 

918.7 

1175.1 

7.78 

.1285 

55 

56 

288.2 

257.6 

917.9 

1175.5 

7.65 

.1307 

56 

57 

289.4 

258.8 

917.1 

1175.9 

7.52 

.1329 

57 

58 

290.5 

259.9 

916.2 

1176.1 

7.40 

.1351 

58 

59 

291.6 

261.1 

915.4 

1176.5 

7.28 

.1373 

59 

60 

292.7 

262.2 

914.6 

1176.8 

7.17 

.1394 

60 

61 

293.8 

263.3 

913.8 

1177.1 

7.06 

.1416 

61 

62 

294.9 

264.4 

.  913.0 

1177.4 

6.95 

.1438 

62 

63 

295.9 

265.5 

912.2 

1177.7 

6.85 

.1460 

63 

64 

297.0 

266.5 

911.5 

1178.0 

6.75 

.1482 

64 

65 

298.0 

267.6 

910.7 

1178.3 

6.65 

.1503 

65 

66 

299.0 

268.6 

910.0 

1178.6 

6.56 

.1525 

66 

67 

300.0 

269.7 

909.2 

1178.9 

'  6.47 

.1547 

67 

68 

301.0 

270.7 

908.4 

1179.1 

6.38 

.1569 

68 

69 

302.0 

271.7 

907.7 

1179.4 

6.29 

.1591 

69 

70 

302.9 

272.7 

906.9 

1179.6 

6.20 

.1612 

70 

71 

303.9 

273.7 

906.2 

1179.9 

6.12 

.1634 

71 

72 

304.8 

274.6 

905.5 

1180.1 

6.04 

.1656 

72 

73 

305.8 

275.6 

904.8 

1180.4 

5.96 

.1678 

73 

74 

306.7 

276.6 

904.1 

1180.7 

5.89 

.1699 

74 

75 

307.6 

277.5 

903.4 

1180.9 

5.81 

.1721 

75 

76 

308.5 

278.5 

902.7 

1181.2 

5.74 

.1743 

76 

77 

309.4 

279.4 

902.1 

1181.5 

5.67 

.1764 

77 

78 

310.3 

280.3 

901.4 

1181.7 

5.60 

.1786 

78 

79 

311.2 

281.2 

900.7 

1181.9 

5.54 

.1808 

79 

80 

312.0 

282.1 

900.1 

1182.2 

5.47 

.1829 

80 

81 

312.9 

283.0 

899.4 

1182.4 

5.41 

.1851 

81 

82 

313.8 

283.8 

898.8 

1182.6 

5.34 

.1873 

82 

83 

314.6 

284.7 

898.1 

1182.8 

5.28 

.1894 

83 

84 

315.4 

285.6 

897.5 

1183.1 

5.22 

.1915 

84 

85 

316.3 

286.4 

896.9 

1183.3 

5.16 

.1937 

85 

STEAM,  FUELS  AND  COMBUSTION  19 

TABLE  3.— PROPERTIES  OF  SATURATED  STEAM— Continued 
English  Units  — 


11 

1^ 

Specific 

Volume 

Cu.  Ft.  per 

Pound 

p 

t 

h 

L 

H 

V 

»~ 

p 

86 

317.1 

287.3 

896.2 

1183.5 

5.10 

.1959 

86 

87 

317.9 

288.1 

895.6 

1183.7 

5.05 

.1980 

87 

88 

318.7 

288.9 

895.0 

1183.9 

5.00 

.2002 

88 

89 

319.5 

289.8 

894.3 

1184.1 

4.94 

.2024 

89 

90 

320.3 

290.6 

893.7 

1184.3 

4.89 

.2045 

90 

91 

321.1 

291.4 

893.1 

1184.5 

4.84 

.2066 

91 

92 

321.8 

292.2 

892.5 

1184.7 

4.79 

.2088 

92 

93 

322.6 

293.0 

891.9 

1184.9 

4.74 

.2110 

93 

94 

323.4 

293.8 

891.3 

1185.1 

4.69 

.2131 

94 

95 

324.1 

294.5 

890.7 

1185.2 

4.65 

.2152 

95 

96 

324.9 

295.3 

890.1 

1185.4 

4.69 

.2173 

96 

97 

325.6 

296.1 

889.5 

1185.6 

4.56 

.2194 

97 

98 

326.4 

296.8 

889.0 

1185.8 

4.51 

.2215 

98 

99 

327.1 

297.6 

888.4 

1186.0 

4.47 

.2237 

99 

100 

327.8 

298.4 

887.8 

1186.2 

4.430 

.2257 

100 

101 

328.6 

299.1 

887.2 

1186.3 

4.389 

.2278 

101 

102 

329.3 

299.8 

886.7 

1186.5 

4.349 

.2299 

102 

103 

330.0 

300.6 

886.1 

1186.7 

4.309 

.2321 

103 

104 

330.7 
33lk 

301.3 

885.6 

1186.9 

4.270 

.2342 

104 

105 

302.0 

885.0 

1187.0 

4.231 

.2364 

105 

106 

332.0 

302.7 

884.5 

1187.2 

4.193 

.2385 

106 

107 

332.7 

303.4 

883.9 

1187.3 

4.156 

.2407 

107 

108 

333.4 

304.1 

883.4 

1187.5 

4.119 

.2428 

108 

109 

334.1 

304.8 

882.8 

1187.6 

4.082 

.2450 

109 

110 

334.8 

305.5 

882.3 

1187.8 

4.047 

.2472 

110 

111 

335.4 

306.2 

881.8 

1188.0 

4.012 

.2493 

111 

112 

336.1 

306.9 

881.2 

1188.1 

3.977 

.2514 

112 

113 

336.8 

307.6 

880.7 

1188.3 

3.944 

.2535 

113 

114 

337.4 

308.3 

880.2 

1188.5 

3.911 

.2557 

114 

114.7 

337.9 

308.8 

879.8 

1188.6 

3.888 

.2572 

114.7 

115 

338.1 

309.0 

879.7 

1188.7 

3  878 

.2578 

115 

116 

338.7 

309.6 

879.2 

1188.8 

3.846 

.2600 

116 

117 

339.4 

310.3 

878.7 

1189.0 

3.815 

.2621 

117 

118 

340.0 

311.0 

878.2 

1189.2 

3.784 

.2642 

118 

119 

340.6 

311.7 

877.6 

1189.3 

3.754 

.2663 

119 

120 

341.3 

312.3 

877.1 

1189.4 

3.725 

.2684 

120 

121 

341.9 

313.0 

876.6 

1189.6 

3.696 

.2706 

121 

122 

342.5 

313.6 

876.1 

1189.7 

3.667 

.2727 

122 

123 

343.2 

314.3 

875.6 

1189.9 

3.638 

.2749 

123 

20 


FARM  MOTORS 


TABLE  3.— PROPERTIES  OF  SATURATED  STEAM— Continued 
English  Units 


is 

si 

r 

li  • 

u 

Specific 

Volume 

Cu.  Ft.  per 

Pound 

lis 

V 

t 

h 

L 

H 

V 

1 

V 

p 

124 

343.8 

314.9 

875.1 

1190.0 

3.610 

.2770 

124 

125 

344.4 

315.5 

874.6 

1190.1 

3.582 

.2792 

125 

126 

345.0 

316.2 

874.1 

1190.3 

3.555 

.2813 

126 

127 

345.6 

316.8 

873.7 

1190.5 

3.529 

.2834 

127 

128 

346.2 

317.4 

873.2 

1190.6 

3.503 

.2855 

128 

129 

346.8 

318.0 

872.7 

1190.7 

3.477 

.2876 

129 

130 

347.4 

318.6 

872.2 

1190.8 

3.452 

.2897 

130 

131 

348.0 

319.3 

871.7 

1191.0 

3.427 

.2918 

131 

132 

348.5 

319.9 

871.2 

1191.1 

3.402 

.2939 

132 

133 

349.1 

320.5 

870.8 

1191.3 

3.378 

.2960 

133 

134 

349.7 

321.0 

870.4 

1191.4 

3.354 

.2981 

134 

135 

350.3 

321.6 

869.9 

1191.5 

3.331 

.3002 

135 

136 

350.8 

322.2 

869.4 

1191.6 

3.308 

.3023 

136 

137 

351.4 

322.8 

868.9 

1191.7 

3.285 

.3044 

137 

138 

352.0 

323.4 

868.4 

1191.8 

3.263 

.3065 

138 

139 

352.5 

324.0 

868.0 

1192.0 

3.241 

.3086 

139 

140 

353.1 

324.5 

867.6 

1192.1 

3.219 

.3107 

140 

141 

353.6 

325.1 

867.1 

1192.2 

3.198 

.3128 

141 

142 

354.2 

325.7 

866.6 

1192.3 

3.176 

.3149 

142 

143 

354.7 

326.3 

866.2 

1192.5 

3.155 

.3170 

143 

144 

355.3 

326.8 

865.8 

1192.6 

3.134 

.3191 

144 

145 

355.8 

327.4 

865.3 

1192.7 

3.113 

.3212 

145 

146 

356.3 

327.9 

864.9 

1192.8 

3.093 

.3233 

146 

147 

356.9 

328.5 

864.4 

1192.9 

3.073 

.3254 

147 

148 

357.4 

329.0 

864.0 

1193.0 

3.053 

.3275 

148 

149 

357.9 

329.6 

863.5 

1193.1 

3.033 

.3297 

149 

150 

358.5 

330.1 

863.1 

1193.2 

3.013 

.3319 

150 

152 

359.5 

331.2 

862.3 

1193.5 

2.975 

.3361 

152 

154 

360.5 

332.3 

861.4 

1193.7 

2.939 

.3403 

154 

156 

361.6 

333.4 

860.5 

1193.9 

2.903 

.3445 

156 

158 

362.6 

334.4 

859.7 

1194.1 

2.868 

.3487 

158 

160 

363.6 

335.5 

858.8 

1194.3 

2.834 

.3529 

160 

162 

364.6 

336.6 

858.0 

1194.6 

2.801 

.3570 

162 

164 

365.6 

337.6 

857.2 

1194.8 

2.768 

.3613 

164 

166 

366.5 

338.6 

856.4 

1195.0 

2.736 

.3655 

166 

168 

367.5 

339.6 

855.5 

1195.1 

2.705 

.3697 

168 

170 

368.5 

340.6 

854.7 

1195.3 

2.674 

.3739 

170 

172 

369.4 

341.6 

853.9 

1195.5 

2.644 

.3782 

172 

174 

370.4 

342.5 

853.1 

1195.6 

2.615 

.3824 

174 

176 

371.3 

343.5 

852.3 

1195.8 

2.587 

.3865 

176 

STEAM,  FUELS  AND  COMBUSTION 


21 


TABLE  3.— PROPERTIES  OF  SATURATED  STEAM— Continued 
English  Units 


it 

Specific 

Volume 

Cu.  Ft.  per 

Pound 

aid 

P 

t 

h 

L 

H 

V 

I 

p 

178 

372.2 

344.5 

851.5 

1196.0 

2.560 

.3907 

178 

180 

373.1 

345.4 

850.8 

1196.2 

2.532 

.3949 

180 

182 

374.0 

346.4 

850.0 

1196.4 

2.506 

.3990 

182 

184 

374.9 

347.4 

849.3 

1196.7 

2.480 

.4032 

184 

186 

375.8 

348.3 

848.5 

1196.8 

2.455 

.4074 

186 

188 

376.7 

349.2 

847.7 

1196.9 

2.430 

.4115 

188 

190 

377.6 

350.1 

847.0 

1197.1 

2.406 

.4157 

190 

192 

378.5 

351.0 

846.2 

1197.2 

2.381 

.4200 

192 

194 

379.3 

351.9 

845.5 

1197.4 

.  2.358 

.4242 

194 

196 

380.2 

352.8 

844.8 

1197.6 

2.335 

.4284 

196 

198 

381.0 

353.7 

844.0 

1197.7 

2.312 

.4326 

198 

200 

38L9 

354.6 

843.3 

1197.9 

2.289 

.4370 

200 

202 

382.7 

355.5 

842.6 

1198.1 

2.268 

.4411 

202 

204 

383.5 

356.4 

841.9 

1198.3 

2.246 

.4452 

204 

206 

384.4 

357.2 

841.2 

1198.4 

2.226 

.4493 

206 

208 

385.2 

358.1 

840.5 

1198.6 

2.206 

.4534 

208 

210 

386.0 

358.9 

839.8 

1198.7 

2.186 

.4575 

210 

212 

386.8 

359.8 

839.1 

1198.9 

2.166 

.4618 

212 

214 

387.6 

360.6 

838.4 

1199.0 

2.147 

.4660 

214 

216 

388.4 

361.4 

837.7 

1199.1 

2.127 

.4700 

216 

218 

389.1 

362.3 

837.0 

1199.3 

2.108 

.4744 

218 

220 

389.9 

363.1 

836.4 

1199.5 

2.090 

.4787 

220 

222 

390.7 

363.9 

835.7 

1199.6 

2.072 

.4829 

222 

224 

391.5 

364.7 

835.0 

1199.7 

2.054 

.4870 

224 

226 

392.2 

365.5 

834.3 

1199.8 

2.037 

.4910 

226 

228 

393.0 

366.3 

833.7 

1200.0 

2.020 

.4950 

228 

230 

393.8 

367.1 

833.0 

1200.1 

2.003 

.4992 

230 

232 

394.5 

367.9 

832.3 

1200.2 

1.987 

.503 

232 

234 

395.2 

368.6 

831.7 

1200.3 

1.970 

.507 

234 

236 

396.0 

369.4 

831.0 

1200.4 

1.954 

.511 

236 

238 

396.7 

370.2 

830.4 

1200.6 

1.938 

.516 

238 

240 

397.4 

371.0 

829.8 

1200.8 

1.923 

.520 

240 

242 

398.2 

371.7 

829.2 

1200.9 

1.907 

.524 

242 

244 

398.9 

372.5 

828.5 

1201.0 

1.892 

.528 

244 

246 

399.6 

373.3 

827.8 

1201.1 

1.877 

.532 

246 

248 

400.3 

374.0 

827.2 

1201.2 

1.862 

.537 

248 

250 

401.1 

374.7 

826.6 

1201.3 

1.848 

.541 

250 

275 

409.6 

383.7 

819.0 

1202.7 

1.684 

.594 

275 

300 

417.5 

392.0 

811.8 

1203.8 

1.547 

.647 

300 

350 

431.9 

407.4 

798.5 

1205.9 

1.330 

.750 

350 

22  FARM  MOTORS 

for  steam  generation  on  account  of  the  injuri(  us  sulphurous  acid 
formed  when  the  fuel  is  burned. 

Wood  is  but  little  used  for  steam  generation  except  in  remote 
places,  where  timber  is  plentiful  or  in  special  cases  where  sawdust, 
shavings  and  pieces  of  wood  are  a  by-product  of  manufacturing 
operations.  Wood  burns  rapidly  and  with  a  bright  flame,  but 
does  not  evolve  much  heat.  When  first  cut,  wood  contains  30  to 
50  per  cent,  of  moisture  which  can  be  reduced  by  drying  to  about 
15  per  cent.  One  pound  of  dry  wood  is  equal  in  heat-producing 
value  to  4/10  lb.  of  soft  coal.  It  is  important  that-wood  be  dry 
as  each  10  per  cent,  of  moisture  reduces  its  heat-producing  value 
as  a  fuel  by  about  12  per  cent. 

Coal  is  more  extensively  used  as  a  fuel  foj  steam  generation 
than  any  other  substance.  All  coals  are  derived  from  vegetable 
origin  and  are  classified  as  follows : 

1.  Anthracite,  or  hard  coal  consisting  mainly  of  carbon. 
This  coal  is  slow  to  ignite,  burns  with  very  little  flame,  produces 
and  gives  off  very  little  smoke.  Anthracite  coal  contains  very 
little  volatile  matter  and  may  contain  none. 

2.  Semi-anthracite  coal  is  softer  and  fighter  than  anthracite, 
and  contains  less  carbon  and  from  7  to  12  per  cent,  volatile  matter. 

3.  Semi-bituminous,  which  contains  from  12  to  25  per  cent, 
volatile  matter  and  less  fixed  carbon  than  the  semi-anthracite. 

4.  Bituminous,  or  soft  coal  contains  more  than  20  per  cent, 
of  volatile  matter  and  only  about  50  per  cent,  of  fixed  carbon. 

5.  Lignite,  which  may  be  classified  as  soft  coal,  arrested  in 
the  process  of  formation.  This  coal  contains  a  very  large  pro- 
portion of  volatile  matter  and  less  than  50  per  cent,  fixed  carbon. 
However,  it  has  a  good  heating  value  and  is  usually  a  free  burner, 
but  owing  to  the  high  percentage  of  volatile  matter  it  will  not 
stand  storage,  but  crumbles  badly  soon  after  exposure  to  air. 

Other  solid  fuels  used  to  some  extent  for  steam  generation  are : 
Peat,  which  is  an  intermediate  between  wood  and  coal  and  found 
in  bogs,  sawdust,  spent  oak  bark  after  having  been  used  in  the 
process  of  tanning,  bagasse  or  the  refuse  of  cane  sugar,  and  cotton 
stalks.  Coke  is  also  used  to  some  extent,  the  advantage  of  this 
fuel  as  compared  with  coal  being  that  coke  will  not  ignite  spon- 
taneously, will  not  deteriorate  or  decompose  when  exposed  to 
the  atmosphere,  and  produces  no  smoke  when  burned.     Coke  is 


STEAM,  FUELS  AND  COMBUSTION 


23 


manufactured  by  burning  coal  in  a  limited  air  supply,  the  volar^ 
tile  hydrocarbons  being  driven  off  during  the  process. 

Petroleum  fuels  either  in  the  form  of  crude  petroleum,  or  as 
the  refuse  left  from  its  distillation,  are  used  for  making  steam  to 
a  considerable  extent  in  certain  parts  where  the  relative  cost  of 
oil  is  less  than  that  of  coal.  It  has  been  estimated  that  petro- 
leum oils  at  2  cents  per  gallon  are  equally  economical  for  steam 
making  as  coal  at  $3  per  ton.  The  advantages  of  oil  as  com- 
pared with  solid  fuels  are  ease  of  handling,  cleanliness  and 
absence  of  smoke  after  combustion. 

Natural  gas  is  used  for  steam  generation  where  its  cost  is  low. 
If  the  cost  of  natural  gas  is  greater  than  10  cents  per  thousand 
cubic  feet  it  cannot  compete  with  coal  at  $3  a  ton.  Illuminating 
gas  is  too  expensive  for  steam  generation  and  cannot  compete 
with  other  fuels. 

Combustion. — Combustion  is  a  chemical  combination  of  the 
heat  producing  constituents  of  a  fuel  with  oxygen  and  is  accom- 
panied by  the  production  of  heat  and  light.  The  supply  of  oxy- 
gen for  combustion  is  taken  from  the  atmosphere,  every  pound 
of  air  consisting  of  0.23  parts  by  weight  of  oxygen  and  0.77  parts 
by  weight  of  nitrogen. 

It  has  been  found  that  most  coals  require  between  11  and  12 
lb.  of  air  for  every  pound  of  coal  burned  and  that  the  heat  de- 
veloped during  the  combustion  of  1  lb.  of  the  various  fuels  is 
as  follows: 


TABLE  4.— HEAT  DEVELOPED  BY  THE  COMBUSTION  OF  VARI- 

OUS  FUELS 


Name  of  fuel 


Heat  developed  in 
B.t.u.  per  pound 
of  fuel 


Heat  developed  in 

B.t.u.   per   cubic 

foot  of  fuel 


Anthracite  coal 

Semi-bituminous  coal . . 

Bituminous  coal 

Lignite 

Peat  (dry) 

Wood 

Petroleum  fuels 

Alcohol  (100  per  cent.) , 

Natural  gas 

Illuminating  gas 

Producer  gas 


13,200  to  13,900 

13,000  to  16,000 

12,000  to  15,000 

8,500  to  11,400 

8,000  to  11,000 

8,200  to    9,200 

18,000  to  20,000 

11,500 


900  to  1000 
600  to  700 
100  to  150 


24  FARM  MOTORS 

Commercial  Value  of  Fuels. — In  the  furnace  of  the  actual 
boiler  plant  only  30  to  70  per  cent,  of  the  heat  units  contained 
in  the  given  fuel  is  utilized  for  the  generation  of  steam.  The  princi- 
pal losses  in  the  boiler  furnace  are  due  to  incomplete  combustion, 
infiltration  of  air  through  setting,  and  to  the  heat  carried  away 
in  the  flue  gases.  The  methods  to  be  employed  in  order  to  re- 
duce these  losses  to  a  minimum  will  be  discussed  under  boiler 
management. 

PROBLEMS 

1.  Calculate  the  heat  contained  in  1  lb.  of  dry  steam  at  100  lb.  gage. 

2.  If  the  steam  in  the  above  problem  contained  5  per  cent,  moistm-e,  how 
much  less  heat  would  that  pound  of  steam  have  as  compared  with  dry  steam? 

3.  Calculate  the  volume  of  3  lb.  of  steam  at  atmospheric  pressure,  and  also 
at  a  pressure  of  150  lb.  gage. 

4.  If  steam  at  a  pressure  of  120  lb.  has  a  temperature  of  390°  F.,  is  it 
saturated? 

5.  Taking  the  weight  of  a  gallon  of  water  as  8  1/3  lb.  and  using  the  values 
given  in  Tables  2  and  4,  compare  the  heat  units  contained  in  a  gallon  of 
gasoline  and  kerosene. 

6.  If  a  ton  of  ice  melts  in  24  hours,  how  much  heat  will  it  abstract  during 
that  time  from  the  surrounding  substances? 


CHAPTER  IV 
STEAM  BOILERS  AND  AUXILIARIES 

Principal  Parts  of  a  Steam  Power  Plant. — The  principal  parts 
of  a  steam  power  plant  are  illustrated  in  Fig.  3,  and  include  the 
following : 

A  furnace  in  whch  the  fuel  is  burned.  This  consists  of  a 
chamber  arranged  with  a  grate  I,  if  coal  or  any  other  solid  fuel 


Fig.  3. 

is  used,  and  with  burners  when  the  fuel  is  in  the  liquid  or  gaseous 
state.  The  furnace  is  connected  through  a  flue  or  breeching  2 
to  a  chimney.     The  function  of  a  chimney  is  to  produce  suffi- 

25 


26  FARM  MOTORS 

cient  draft,  so  that  the  fuel  will  have  the  proper  amount  of  air 
for  combustion;  it  also  serves  to  carry  off  the  obnoxious  gases 
after  the  combustion  process  is  completed.  The  flue  leading  to 
the  chimney  is  provided  with  a  damper  3,  so  that  the  intensity 
of  the  draft  can  be  regulated. 

A  boiler  4,  which  is  a  closed  metalHc  vessel  filled  to  about  two- 
thirds  of  its  volume  with  water.  The  heat  developed  by  burning 
the  fuel  in  the  furnace  is  utilized  in  converting  the  water  con- 
tained in  the  boiler  into  steam.  The  boiler  4  is  arranged  with 
a  water  column  5  to  show  the  water  level,  with  a  safety  valve  6 
to  prevent  the  pressure  from  rising  too  high,  and  with  a  gage  7 
to  indicate  the  steam  pressure. 

Boiler  Setting. — The  function  of  a  setting  is  to  provide  cor- 
rects paces  for  the  furnace,  combustion  chamber  and  ash  pit,  to 
support  the  boiler  shell,  to  prevent  air  from  entering  the  fur- 
nace above  the  fuel  bed,  and  to  decrease  the  heat  radiation  to 
a  minimum. 

The  feed  pump  8  supplies  the  boiler  with  water  through  the 
feed  pipe  9. 

The  steam  lines  10  and  11  convey  steam  from  the  boiler  to 
the  engine  and  to  the  steam  end  of  the  pump  respectively. 

In  the  engine  the  energy  of  the  steam  is  expended  in  doing 
work.  The  steam  enters  the  engine  cylinder  12  through  the  valve 
13  and  pushes  on  the  piston  14.  The  sHding  motion  of  the  pis- 
ton, which  is  transmitted  to  the  piston  rod  15,  is  changed  into 
rotary  motion  at  the  shaft  16  by  means  of  a  connecting  rod  17 
and  crank  18. 

The  exhaust  pipe  19  conveys  the  used  steam  to  the  atmosphere, 
condenser  or  to  some  use  where  its  heat  is  abstracted,  converting 
the  steam  back  into  water. 

Classification  of  Boilers. — Boilers  are  divided  into  fire-tube 
and  water-tube  types.  In  the  fire-tube  the  hot  gases  developed 
by  the  combustion  of  the  fuel  pass  through  the  tubes,  while 
in  the  water-tube  boilers  these  gases  pass  around  the  tubes. 
Either  type  may  be  constructed  as  a  vertical  or  as  a  horizontal 
boiler  depending  on  whether  the  axis  of  the  shell  is  vertical  or 
horizontal. 

The  fire-tube  boiler  may  be  externally  or  internally  fired. 
In  the  externally  fired  boiler  the  furnace  is  in  the  setting  entirely 


STEAM  BOILERS  AND  AUXILIARIES 


27 


outside  of  the  boiler  shell,  while  in  the  internally  fired  types  the  _ 
furnace  is  in  the  boiler  shell,  no  brick  setting  being  necessary. 


^^^^^^^^^^^^^^^^^^^  A^ 


Fig.  4. 


For  stationary  work  the  externally  fired  boiler  is  most  common, 
while  the  internally  fired  types  are  always  used  for  locomotive 


Fig.  5. 


and  traction  engine   purposes  and  generally  for  marine   use. 
Vertical  fire-tube  boilers  are  usually  internally  fired. 


28 


FARM  MOTORS 


Return  Tubular  Boiler. — Boilers  of  this  type  are  most  com- 
monly used  in  this  country.  The  general  appearance  of  a  boiler 
of  this  type  is  shown  in  Figs.  4  and  5.  Fig.  6  illustrates  the 
details  of  the  setting. 


These  boilers  as  seen  from  the  cuts  consist   of  a    cylindrical 
shell  closed  at  the  end  by  two  flat  heads,  and  of  numerous  small 


Fig.  7. 


tubes  which  extend  the  whole  length  of  the  shell.  Two-thirds 
of  the  volume  of  the  shell  is  filled  with  water,  the  remaining  part 
being  left  for  the  disengagement  of  the  steam  from  the  water, 


STEAM  BOILERS  AND  AUXILIARIES 


29 


Fig.  8. 


Fig.  9. 


30 


FARM  MOTORS 


and  called  the  steam  space.  Sometimes,  as  shown  in  Fig.  7,  a 
steam  dome  D  is  provided  to  increase  the  volume  of  the  steam 
space.  The  coal  burns  upon  the  grates  which  as  shown  in  Fig. 
6,  rest  upon  the  bridge  wall  W  and  upon  the^front  of  the  setting. 
The  gases  pass  from  the  furnace  under  and  along  the  boiler  shell 
to  the  back  connection  or  combustion  chamber  C,  and  from 
there  to  the  front  through  the  tubes  and  up  the  uptake  to  the 
breeching  or  flue  which  leads  to  the  chimney. 

Boilers  of  this  type  are  usually  set  in  brick  settings.  The 
boiler  may  be  supported  by  brackets,  as  shown  in  Fig.  5, 
the  front  ones  resting  directly  on  the  side  walls,  while  the  back 


Fig.  10. 


brackets  are  placed  on  rollers  which  in  turn  rest  on  horizontal 
plates,  this  method  allowing  the  back  of  the  boiler  to  move 
as  the  shell  expands.  A  better  method  is  to  support  the  boiler 
independent  of  the  setting  on  steel  framework  as  shown  in  Fig.  8. 
The  upper  portion  of  the  boiler  shell  should  be  covered  so  that  the 
hot  gases  will  not  come  in  contact  with  the  shell  above  the  water 
line. 

Internally  Fired  Boilers. — While  the  externally  fired  boiler 
is  most  commonly  used,  the  internally  fired  type  shown  in  Fig.  9 
is  also  used  to  some  extent.     In  these  boilers  the  fire  does  not 


STEAM  BOILERS  AND  AUXILIARIES 


31 


come  in  contact  with  the  boiler  shell,  and  this  permits  the  con^ 
struction  of  larger  boilers  and  the  carrying  of  greater  pressures 
on  account  of  the  allowable  greater  thickness  of  shell. 

The  locomotive  type  of  boiler  shown  in  Fig.  10  is  a  special 


H^^^^^Hk.9  a  tifi^^^Hi 


Fig.  11. 


Fig.  12. 


type  of  the  internally  fired  boilers.  This  type  of  boiler  is 
sometimes  used  for  stationary  purposes.  It  has  no  permanent 
foundation. 

Vertical  Fire-tube  Boilers.— Two  forms  of  vertical  boilers  are 


32 


FARM  MOTORS 


Fig.  13. 


Fig.  14. 


STEAM  BOILERS  AND  AUXILIARIES  33 

shown  in  Figs.  11  and  12.  In  the  form  shown  in  Fig.  11  the  tops 
of  the  tubes  are  above  the  water  line  and  may  become  overheated 
when  the  boiler  is  forced.  To  prevent  injury  from  this  cause, 
some  forms  of  vertical  boilers  are  constructed  as  shown  in  Fig.  12, 
the  tops  of  the  tubes  being  ended  in  a  submerged  tube  sheet 
which  is  kept  below  the  water  line. 

The  essential  parts  of  all  forms  of  vertical  boilers  are  a  cylin- 
drical shell  with  a  firebox  and  ash  pit  in  the  lower  end.  The 
tubes  lead  directly  from  the  furnace  to  the  upper  head  of  the 
shell.     The  hot  gases  from  the  furnace  pass  through  the  tubes 


Fig.  15. 

and  out  of  the  stack.  The  firebox  is  surrounded  with  water  as 
in  the  case  of  the  locomotive  boiler. 

Vertical  boilers  occupy  little  floor  space  and  require  no  setting 
or  foundation.     They  can  also  be  used  as  portable  boilers. 

Water  Tube  Boilers. — Water  tube  boilers  are  used  in  large 
power  plants  on  account  of  their  adaptability  to  higher  pressures 
and  larger  sizes,  decreased  danger  from  serious  explosions, 
greater  space  economy,  and  rapidity  of  steam  generation.  For 
small  power  plants  the  fire  tube  boiler  is  usually  more  suitable 
on  account  of  its  lower  first  cost.  Also  in  a  fire  tube  boiler  if  a 
tube  should  break,  the  boiler  can  be  repaired  by  plugging  without 


34 


FARM  MOTORS 


interrupting  service,  which  is  not  the  case  with  most  types  of 
water  tube  boilers.  As  far  as  economy  is  concerned,  numerous 
tests  show  that  either  type  when  properly  designed  and  operated 
will  give  the  same  economy. 

There  are  many  different  types  of  water  tube  boilers  on  the 
market,  but  the  essential  parts  of  all  are  tubes  filled  with  water 
and  one  or  more  drums  for  the  disengagement  of  the  steam  from 
the  water. 


I'IG.    16. 


Water  tube  boilers  are  commonly  divided  into  three  classes: 
In  one  class  the  tubes  are  fastened  into  several  sets  of  headers, 
which  are  connected  to  a  common  drum.  The  Babcock  and  Wil- 
cox boiler  shown  in  Fig.  13  represents  this  class.  The  hot  gases 
from  the  furnace  are  directed  by  means  of  fire  brick  baffle  plates 
and  by  the  bridge-wall  to  pass  across  the  tubes  three  times  on  the 
way  to  the  uptake  at  the  back  of  the  boiler. 

In  another  type  the  Heine,  shown  in  Fig.  14,  all  the  tubes  end 


STEAM  BOILERS  AND  AUXILIARIES 


35 


in  one  common  header  at  each  end.     In  this  type  the  baffle  plates~ 
are  arranged  horizontally  so  that  the  hot  gases  pass  along  the 
tubes  several  times  on  the  way  to  the  breeching. 

Under  the  third  type  are  included  water  tube  boilers  which  have 
more  than  one  drum  connected  by  tubes.  The  Stirling  and 
Wickes  shown  in  Figs.  15  and  16  are  examples  of  these  types. 

Grates  for  Boiler  Furnaces. — Grates  are  formed  of  cast-iron 


Fig.  18. 

bars.  Several  forms  of  grate  bars  are  illustrated  in  Figs.  17  and 
18.  Plain  grates  are  best  adapted  for  caking  coals  and  are 
usually  provided  with  iron  bars  cast  in  pairs  and  lugs  at  the  side. 
The  Tupper  type  of  grate  is  more  suitable  for  the  burning  of 
hard  coal  which  does  not  cake.     The  grates  of  a  boiler  furnace  can 


Fig.  17. 

be  easily  interchanged  to  suit  the  fuel  burned.  For  most  eco- 
nomical results  some  form  of  rocking  and  dumping  grate,  as  shown 
in  Fig.  18,  should  be  used. 

Piping  for  Boilers. — Pipes  used  for  carrying  steam  are  made  of 
wrought  iron  or  steel.     Wrought  iron  pipe  is  superior  to  steel 


36 


FARM  MOTORS 


^M 


Fig.  21. 


Fig.  19. 


Fig.  20. 


Fig.  22. 


Fig.  23. 


Fig.  24. 


Fig.  25. 


STEAM  BOILERS  AND  AUXILIARIES  37 

pipe  as  far  as  durability  is  concerned,  but  is  more  expensive  and~ 
more  difficult  to  secure.  Sizes  of  steam  pipe  are  named  by  the 
inside  diameter,  while  boiler  tubes  go  by  the  outside  diameter. 
Standard  steam  pipe  is  made  in  sizes  of  1/8,  1/4,  3/8,  1/2,  3/4, 
1,  1  1/4,  1  1/2,  2,  2  1/2,  3,  3  1/2,  4,  4  1/2,  5,  6,  7,  8,  9,  10,  11  and 
12  in.     Sizes  above  12  in.  are  named  by  the  outside  diameter. 

The  various  grades  of  pipe  are  merchant,  standard,  extra 
heavy  and  double  extra  heavy.  Merchant  pipe  is  somewhat 
lighter  than  standard  pipe  and  its  manufacture  is  being  discon- 
tinued. Extra  heavy  and  double  extra  heavy  have  the  same  out- 
side diameters  as  standard  pipe,  but  the  inside  diameters  are 
smaller,  due  to  the  greater  thickness  of  the  pipe. 

Steam  pipe  lines  should  always  be  laid  with  a  gradual  inclina- 
tion downward,  so  as  to  allow  the  condensation  that  occurs  to 
flow  in  the  direction  in  which  steam  is  moving.  If  this  is  not  done 
water  may  accumulate,  will  be  picked  up  by  the  steam  and  may 
cause  much  damage  by  water  hammer. 

Pipe  Fittings. — Figure  19  illustrates  several  forms  of  pipe 
unions,  which  are  used  for  uniting  two  lengths  of  pipe. 

The  elbow  or  ell  shown  in  Fig.  20  is  employed  for  connecting 
two  pipes  of  the  same  size  and  at  right  angles  to  each  other.  If 
the  pipes  are  of  different  diameters  a  reducing  ell  as  shown  in 
Fig.  21  should  be  used. 


Fig.  26.  Fig.  27. 


The  tee  shown  in  Fig.  22  is  used  for  making  a  branch  at  right 
angles  to  a  pipe  line. 

The  cross  shown  in  Fig.  23  is  used  when  two  branches  must  be 
made  in  opposite  directions. 

In  order  to  reduce  the  size  of  a  pipe  line  a  bushing.  Fig.  24,  or 
a  reducer.  Fig.  25,  can  be  used. 

To  close  the  end  of  a  pipe  a  cap.  Fig.  26,  is  used,  while  the  plug 
shown  in  Fig.  27  is  used  to  close  a  pipe  threaded  on  the  inside  or 
a  fitting. 


38 


FARM  MOTORS 


/=^^ 


Fig.  28. 


Fig.  29. 


Fig.  30. 


STEAM  BOILERS  AND  AUXILIARIES 


39 


Valves. — The  function  of  a  valve  is  to  control  and  regulate  tbe  ~ 
flow  of  water,  steam  or  gas  in  a  pipe.     In  the  globe  valve  in  Fig. 
28  the  fluid  usually  enters  at  the  right,  passes  under  the  valve  and 
out  at  the  left. 


Fig. 


This  method  of  installation  places  the  pressure  of  the  steam,  or 
other  fluid,  against  the  disc  in  such  a  way  that  it  tends  to  open  the 
valve.     The  advantages  claimed  for  this  method  are : 

1.  When  the  valve  is  closed  the  stems  may  be  packed  without 
cutting  the  steam  pressure  off  the  entire  line. 


Fig.  32. 


2.  The  adjustment  of  the  opening  can  be  made  more  accu- 
rately against  the  steam  pressure  than  with  it. 

3.  The  flow  of  steam  tends  to  keep  the  valve  seat  free  from 
scale  and  other  dirt. 


40 


FARM  MOTORS 


Those  who  favor  the  other  method  claim,  as  the  principal 
advantage,  that  the  pressure  of  the  steam,  when  the  valve  is 
closed,  tends  to  keep  it  in  that  position  and  that  there  is  much  less 
likehhood  of  the  valve  leaking.  Both  methods  will  be  found  in 
use,  but  it  is  probable  that  a  large  majority  of  the  installations 
will  be  found  to  be  in  accordance  with  the  first  method. 

A  gate  valve  is  shown  in  Fig.  29.  This  form  of  valve  gives  a 
straight  passage  through  the  valve,  and  is  preferable  for  most 
purposes  to  the  globe  valve. 

Figure  30  illustrates  an  angle  valve  which  takes  the  place  of 
an  ordinary  valve  and  ell. 


Fig.  33. 


The  function  of  a  check  valve  illustrated  in  Fig.  31  is  to  allow 
water  or  steam  to  pass  in  one  direction  but  not  in  the  other. 

A  boiler  feed  line  should  always  be  provided  with  a  check  valve 
and  also  with  some  form  of  globe  or  gate  valve  to  enable  the 
operator  to  examine  and  repair  the  check  valve. 

Safety  Valves. — The  function  of  a  safety  valve  is  to  prevent 
the  steam  pressure  from  rising  to  a  dangerous  point.  The  two 
common  forms  of  safety  valves  are  the  lever  safety  valve  and  the 
spring  or  pop  safety  valve. 

The  lever  safety  valve  shown  in  Fig.  32  consists  of  a  valve  disc 


STEAM  BOILERS  AND  AUXILIARIES 


41 


which  is  held  down  on  the  valve  seat  by  means  of  a  weight  acting^ 
through  a  lever,  the  steam  pressing  against  the  bottom  of  the 
disc.     The  lever  is  pivoted  at  one  end  to  the  valve  casing  and  is 
marked  at  a  number  of  points  with  the  pressure  at  which  the 


boiler  will  blow  off  if  the  weight  is  placed  at  that  particular  point. 
The  pop  safety  valve  shown  in  Fig.  33  differs  from  the  lever 
valve  in  that  the  valve  disc  is  held  on  its  seat  and  the  steam  pres- 
sure is  resisted  by  a  spring  in  place  of  a  weight  and  lever.     Pop 


42 


FARM  MOTORS 


safety  valves  can  be  adjusted  to  blow  off  at  various  pressures  by 

tightening  or  loosening  the  spring  pressure  on  the  valve  disc. 

Steam  Gages. — A  steam  gage  indicates  the  pressure  of  the 


Fig.  35. 


By-Pass 


steam  in  a  boiler.     The  most  common  form,  shown  in  Fig.  34 
consists  of  a  curved  spring  hollow  tube  closed  at  one  end  and  filled 


STEAM  BOILERS  AND  AUXILIARIES  43 

with  some  liquid.  One  end  of  the  tube  is  free,  while  the  othei^s- 
fastened  to  the  j&tting  which  is  secured  into  the  space  where 
the  pressure  is  to  be  measured.  Pressure  applied  to  the  inside 
of  the  tube  causes  the  free  end  to  move.  This  motion  is  com- 
municated by  means  of  levers  and  small  gears  to  the  needle 
which  moves  over  a  graduated  dial  face,  and  records  the  pressure 
directly  in  pounds  per  square  inch. 

Water  Glass  and  Gage  Cocks. — The  height  of  the  water  level 
in  a  boiler  is  indicated  by  a  water  glass,  one  end  of  which  is  con- 
nected to  the  steam  space  and  the  other  end  to  the  water  space  in 
the  boiler.  All  boilers  should  also  be  provided  with  three  gage 
cocks,  one  of  which  is  set  at  the  desired  water  level,  one  above  and 
one  below.  These  are  more  rehable  than  the  water  glass  and 
should  be  used  for  checking  the  glass. 


Fig.  37. 

Water  Column. — The  steam  gage,  water  glass  and  gage  cocks 
are  usually  fastened  to  a  casting  called  a  water  column.  One 
form  of  water  column  is  shown  in  Fig.  35,  this  also  being  fitted 
with  a  float  and  whistle  to  notify  the  operator  should  the  water 
in  the  boiler  become  too  low  or  too  high.  A  fireman  who  takes 
proper  care  of  the  boilers  in  his  charge  will  never  allow  the  water 
to  be  at  a  height  as  will  necessitate  audible  warning. 

Steam  Traps. — The  object  of  a  steam  trap  is  to  drain  the  water 
from  pipe  lines  without  allowing  the  steam  to  escape.  Two  forms 
of  steam  traps  are  shown  in  Figs.  36  and  37,  the  valve  being 
controlled  by  a  float  when  the  water  in  the  trap  rises  to  a  sufficient 
height. 


44 


FARM  MOTORS 


Feed  Pumps  and  Injectors. — Water  is  forced  into  steam  boilers 
by  pumps  or  injectors.  A  pump  will  handle  water  at  any 
temperature,  while  an  injector  can  be  used  only  when  the  water 


Fig.  38. 

is  cold.  The  injector  is  not  as  wasteful  of  steam  as  a  pump  and 
for  feeding  cold  water  to  a  boiler  has  the  additional  advantage, 
that  it  heats  the  water  while  feeding  it  to  the  boiler. 


y^^Lh.             fe^^^^^^^xr^P^ 

i-l^l 

mui 

=^              1OO2  0 

Fig.  39. 


Feed  pumps  may  be  driven  from  the  cross-head  of  an  engine 
as  is  often  the  case  on  traction  engines.     Such  pumps  are  very 


STEAM  BOILERS  AND  AUXILIARIES 


45 


Fig.  40. 


46 


FARM  MOTORS 


Fig.  41. 


Fig.  42. — Injector. 


STEAM  BOILERS  AND  AUXILIARIES 


47 


simple,  but  can  only  supply  water  to  the  boiler  when  the  engine  is- 
in  operation. 

Direct-acting  steam  pumps,  driven  by  their  own  steam  cyl- 
inders, are  most  commonly  used  for  feeding  boilers,  as  they  can 
be  operated  independently  of  the  main  engine  and  their  speed  can 
be  regulated  to  suit  the  feed  water  demand  of  the  boilers. 

If  a  direct-acting  pump  consists  of  one  steam  cylinder  and  one 
water  cylinder,  as  shown  in  Fig.  38,  it  is  called  a  single  pump. 
Duplex  pumps  have  two  steam  cylinders  and  two  water  cylin- 
ders, as  shown  in  Fig.  39,  the  steam  valve  of  one  being  operated 
from  the  piston  rod  of  the  other. 


Fig.  43. 

The  details  of  construction  of  two  forms  of  direct-acting  pumps 
are  shown  in  Figs.  40  and  41. 

In  the  pump  shown  in  Fig.  40,  1  is  the  steam  cylinder  and  2 
is  the  water  cylinder.  The  valve  E  is  moved  by  the  vibrating 
arm  F  and  admits  steam  into  the  cylinder  1.  If  steam  is  ad- 
mitted at  the  left  of  the  piston  A,  the  piston  will  be  moved  to  the 
right,  pushing  the  plunger  B,  driving  the  water  through  the 
water  valve  K,  and  into  the  feed  line  at  0.     While  the  plunger 


48  FARM  MOTORS 

is  moving  to  the  right,  a  partial  vacuum  is  formed  at  its  left, 
which  opens  the  valve  N  and  drains  the  water  from  the  supply 
at  C.  When  the  plunger  B  reaches  the  extreme  position  to  the 
right,  the  vibrating  arm  F  moves  the  valve  E  to  the  left,  admit- 
ting steam  which  pushes  the  piston  and  plunger  to  the  left,  driv- 
ing the  water  through  the  valve  L  and  taking  a  new  supply 
through  M.  The  function  of  the  air  chamber  P  is  to  secure  a 
steady  flow  of  water  through  the  discharge  0  and  to  prevent 
shock  in  the  piping. 

The  pump  shown  in  Fig.  41  differs  from  the  one  just  described 
in  that  the  steam  valve  G  is  operated  by  the  steam  in  the  steam 
chest  and  not  by  a  vibrating  arm  outside  of  the  cylinder.  The 
piston  C  is  driven  by  steam  admitted  under  the  slide  valve  G,  this 
valve  being  moved  by  a  plunger  F.  This  plunger  F  is  hollow  at 
the  ends  and  the  space  between  it  and  the  head  of  the  steam  chest 
is  filled  with  steam.  Thus  the  plunger  remains  motionless  until 
the  piston  C  strikes  one  of  the  valves  I  exhausting  the  steam 
through  the  part  E  at  one  end.  The  water  end  is  similar  to  that 
of  the  pump  in  Fig.  40. 

Injectors  are  used  very  commonly  for  the  feeding  of  portable 
and  of  small  stationary  boilers.  In  larger  plants  injectors  are 
sometimes  used  in  conjunction  with  pumps  as  an  auxiliary 
method  for  feeding  boilers. 

The  general  construction  of  an  injector  is  illustrated  in  Fig.  42. 
Steam  from  the  boiler  enters  the  injector  nozzle  at  A,  flows 
through  the  combining  tube  BC  and  out  to  the  atmosphere 
through  the  check  valve  E  and  overflow  F.  The  steam  in  ex- 
panding through  the  nozzle  A  attains  considerable  velocity,  and 
forms  sufficient  vacuum  to  cause  the  water  to  rise  to  the  injector. 
The  steam  jet  at  a  high  velocity  coming  in  contact  with  the  water 
is  condensed,  gives  up  its  heat  to  the  water  and  imparts  a  mo- 
mentum which  is  great  enough  to  force  the  water  into  the  boiler 
against  a  steam  pressure  equal  to  or  greater  than  that  of  the 
steam  entering  the  injector. 

As  soon  as  a  vacuum  is  established  in  the  injector  and  the  water 
begins  to  be  delivered  to  the  boiler  the  check  valve  E  at  the  overflow 
closes.  Should  the  flow  of  feed  water  to  the  boiler  be  interrupted, 
due  to  air  leaking  into  the  injector  or  to  some  other  cause,  the 
overflow  will  open  and  the  steam  will  escape  to  the  atmosphere. 


STEAM  BOILERS  AND  AUXILIARIES 


49 


The  method  of  connecting  an  injector  to  a  vertical  boiFerls 
illustrated  in  Fig.  43.  To  facilitate  the  taking  down  of  an  injector 
for  inspection  and  repairs  it  should  be  connected  up  with  unions. 

Due  to  the  fact  that  the  vacuum  in  an  injector  is  broken  as 
the  temperature  of  the  water  increases,  injectors  can  only  work 
when  the  feed  water  is  150°  F.  or  cooler. 


Fig.  44. 


Feed-water  Heaters. — If  cold  water  is  fed  to  a  boiler,  the 
temperature  at  the  place  where  the  water  is  discharged  will  be 
different  from  that  in  the  other  parts  of  the  boiler,  and  strains 
due  to  unequal  expansion  and  contraction  will  be  set  up  which 
will  decrease  the  life  of  the  boiler,  besides  impairing  the  tightness 


50 


FARM  MOTORS 


of  the  setting.  With  hot  feed  water  strains  due  to  unequal 
expansion  are  prevented.  Also  for  every  10°  increase  in  the 
temperature  of  the  feed  water  a  gain  of  about  1  per  cent,  in  the 


Fig.  45. 

fuel  economy  can  be  expected.  This  also  means  that  the  capac- 
city  of  a  boiler  plant  can  be  increased  by  the  installation  of  some 
apparatus,  outside  of  the  boiler,  for  the  heating  of  feed  water. 


STEAM  BOILERS  AND  AUXILIARIES  51 

This  increase  in  capacity  can  usually  be  accomplished  at  muctr 
less  cost  than  by  increasing  the  size  of  the  boiler.  Heating  the 
feed  water  outside  of  the  boiler  serves  also  to  purify  the  water 
before  it  enters  the  boiler. 

Feed-water  can  be  heated  by  live  steam,  by  exhaust  steam, 
or  by  the  waste  chimney  gases. 

The  heating  of  feed  water  by  live  steam  is  not  recommended, 
as  the  advantage  of  this  method  lies  mainly  in  the  amelioration 
of  unequal  expansion. 

Feed-water  heaters  which  utilize  the  heat  of  exhaust  steam 
from  engines  and  pumps  are  most  commonly  used.  Such  heaters 
may  be  constructed  so  that  the  exhaust  steam  and  water  come 
in  direct  contact  and  the  steam  gives  up  its  heat  by  condensation 
Such  heaters  are  called  open  feed-water  heaters.  One  form  of 
open  feed-water  heater  is  shown  in  Fig.  44.  The  water  passes 
over  trays  upon  which  the  impurities  thrown  out  of  the  water  by 
heating  it  are  deposited,  and  can  be  easily  removed. 

If  it  is  desired  to  prevent  the  steam  and  water  from  coming 
in  contact  with  each  other,  some  form  of  closed  heater,  as  shown 
in  Fig.  45,  should  be  used.  In  the  case  of  closed  heaters  the  steam 
on  one  side  of  a  tube,  heats  the  water  on  the  other.  Such 
heaters  may  be  constructed  so  that  either  the  steam  or  the 
water  flows  through  the  tubes. 

Chimneys  and  Artificial  Draft-producing  Systems. — A  chimney 
or  stack  is  used  to  carry  off  the  obnoxious  gases  formed  during  the 
process  of  combustion  at  such  an  elevation  as  will  render  them 
unobjectionable.  Another  very  important  function  performed 
by  a  chimney  is  to  produce  a  draft  which  will  cause  fresh  air, 
carrying  oxygen,  to  pass  through  the  fuel  bed,  producing  continu- 
ous combustion. 

The  draft  produced  by  a  chimney  is  due  to  the  fact  that  the  hot 
gases  inside  the  chimney  are  lighter  than  the  outside  cold  air.  In 
the  boiler  plant  the  cold  air  is  heated  in  passing  through  the  fuel 
bed,  rises  through  the  chimney  and  is  replaced  by  cold  air  entering 
under  the  grate. 

The  amount  of  draft  produced  by  a  chimney  depends  on  its 
height,  the  taller  the  chimney,  the  greater  is  the  draft  produced, 
since  the  difference  in  weight  between  the  column  of  the  inside 
and  that  of  the  air  outside  increases  as  the  height  of  the  chimney. 


52  FARM  MOTORS 

The  intensity  of  chimney  draft  is  measured  in  inches  of  water, 
which  means  that  the  draft  is  strong  enough  to  support  a  column 
of  water  of  the  height  given.  The  draft  produced  by  chimneys  is 
usually  1/2  to  3/4  in.  of  water. 

Chimneys  are  made  of  brick  or  concrete  or  steel.  For  small 
plants  steel  stacks  are  more  desirable.  A  brick  chimney  unless 
carefully  constructed  may  allow  large  quantities  of  air  to  leak  in 
which  will  interfere  with  the  intensity  of  the  draft.  Steel  stacks 
are  also  cheaper.  Brick  chimneys  as  usually  constructed  have 
two  walls,  with  an  air  space  between  them.  The  inside  wall 
should  be  lined  with  fire  brick. 


Fig.  46. 

Draft  produced  by  chimneys  is  called  natural  draft. 

In  some  cases  the  draft  produced  by  chimneys  is  insufficient 
and  some  artificial  method  has  to  be  used. 

Artificial  draft  may  be  produced  by  steam  jets,  as  is  common  in 
locomotive  and  traction-engine  practice.  This  system  is  uneco- 
nomical, and  is  only  used  in  connection  with  land  boilers  to  reduce 
the  clinkering  of  certain  grades  of  coal. 

Firing. — To  the  average  person  firing  consists  merely  of  open- 
ing the  furnace  door  and  throwing  fuel  on  the  grate.     It  has  been 


STEAM  BOILERS  AND  AUXILIARIES 


53 


found  that  some  system  of  firing  must  be  adopted  in  order-^o— __ 
produce  economical  combustion  of  coal. 

The  system  to  be  adopted  depends  mainly  on  the  kind  of  fuel. 


Fig.  47. 


Fig.  48. 


The  spreading  system  consists  of  distributing  a  small  charge  of 
coal  in  a  thin  layer  over  the  entire  grate.     This  system  will 


54  FARM  MOTORS 

give  satisfactory  results  with  anthracite  coal  and  with  some 
bituminous  coals.  With  this  method,  if  the  fuel  is  fed  in  large 
quantities  and  at  long  intervals,  incomplete  combustion  will 
result. 

The  alternate  method  consists  of  covering  first  one  side  of  the 
grate  with  fresh  fuel  and  then  the  other.  The  volatile  gases 
that  pass  off  from  the  fresh  fuel  on  one  side  of  the  grate  are  burned 
with  the  hot  air  coming  from  the  bright  side  of  the  fire.  This 
system  is  best  applied  to  a  boiler  with  a  broad  furnace. 

The  coking  method  is  best  adapted  for  smoky  and  for  the  cak- 
ing varieties  of  bituminous  coal.  In  this  method  the  coal  is  put 
in  the  front  part  of  the  furnace,  and  allowed  to  remain  there  until 
the  volatile  gases  are  driven  off;  it  is  then  pushed  back  and  spread 
over  the  hot  part  of  the  furnace,  and  a  new  charge  is  thrown  in  the 
front. 

Either  one  of  the  three  systems  of  firing  explained  will  produce 
good  results,  if  properly  carried  out  and  if  the  fire  is  kept  bright 
and  clean.  Smoke  indicates  incomplete  combustion  and  with 
bituminous  coal  occurs  if  the  volatile  gases  are  allowed  to  pass  off 
unburned.  If  the  boiler  is  set  too  close  to  the  grate,  the  volatile 
gases  driven  off  from  the  coal  are  brought  in  contact  with  the 
comparatively  cool  surfaces  of  the  boiler  shell  or  tubes  and  smoke 
is  produced. 

Mechanical  Stokers. — In  all  cases  the  best  results  can  be 
obtained  by  firing  coal  frequently  and  in  small  quantities.  With 
mechanical  stokers  this  can  be  accomplished  and  one  man  can 
attend  to  a  large  number  of  furnaces. 

Mechanical  stokers  can  be  arranged  to  feed  or  spread  the  coal 
over  the  fire  or  to  push  the  coal  from  below  the  fire.  Both 
methods  are  illustrated  in  Figs.  46  and  47,  respectively.  Another 
type .  of  stoker  consists  of  an  endless  chain  grate  driven  by  an 
engine.  This  type  of  stoker,  called  the  chain-grate  stoker  is 
illustrated  in  Fig.  48. 

With  mechanical  stokers  inferior  fuels  can  be  burned  without 
smoke,  but  for  small  power  plants  they  are  not  used  on  account  of 
the  initial  high  cost,  large  repair  bills  and  cost  of  power  for  oper- 
ating the  stoker  mechanism. 

Rating  of  Boilers. — Boilers  are  usually  rated  in  horse-power. 
The  term  horse-power  in  this  connection  is  only  a  matter  of  con- 


STEAM  BOILERS  AND  AUXILIARIES  55 

venience  in  rating  boilers,  and  does  not  mean  the  rate  of  doin^ 
work,  but  is  an  arbitrary  unit  applying  to  the  evaporation  of  a 
definite  amount  of  water.  The  American  Society  of  Mechanical 
Engineers  has  recommended  that  one  boiler  horse-power  should 
mean  the  evaporation  of  30  lb.  of  water  per  hour  at  100°  F.  into 
steam  at  70  lb.  gage.  This  is  equivalent  to  the  evaporation  of 
34  1/2  lb.  of  water  from  feed  water  at  212°  F.  into  steam  at  212°  F. 

Boiler  manufacturers  often  rate  boilers  in  square  feet  of  heating 
surface.  It  has  been  found  that  each  square  foot  of  boiler  heat- 
ing surface  can  evaporate  economically  3  to  3.4  lb.  of  water,  so 
that  a  boiler  horse-power  can  be  produced  by  10  to  12  sq.  ft.  of 
boiler  heating  surface. 

Management  of  Boilers. — Before  a  boiler  is  started  for  the  first 
time,  its  interior  should  be  carefully  cleaned,  care  being  taken 
that  no  oily  waste  or  foreign  material  is  left  inside  of  the  boiler. 
The  various  manholes  and  handholes  are  then  closed  and  the 
boiler  is  filled  to  about  two-thirds  of  its  volume  with  water. 
The  fire  is  started  with  wood,  oily  waste  or  other  rapidly  burning 
materials,  keeping  the  damper  and  ash-pit  door  open.  The  fuel 
bed  is  then  built  up  slowly. 

While  getting  up  the  steam  pressure,  the  gage  glass  should 
be  blown  out  to  see  that  it  is  not  choked,  the  gage  cocks  should 
be  tried  and  all  auxiliaries  such  as  pumps,  injectors,  pressure 
gages,  piping,  etc.,  carefully  examined.  The  safety  valve  should 
be  carefully  examined  and  tried  out  before  cutting  the  boiler 
into  service. 

When  cutting  a  boiler  into  service  with  other  boilers,  its  pres- 
sure should  be  the  same  as  that  of  the  other  boilers.  Steam 
valves  should  be  opened  and  closed  very  slowly  in  order  to  pre- 
vent water  hammer  and  stresses  from  rapid  temperature  changes. 

During  the  operation  of  a  steam  boiler  the  safety  valve  should 
be  kept  in  perfect  condition  and  tried  daily  by  allowing  the  pres- 
sure to  rise  gradually  until  the  valve  begins  to  simmer.  Each 
boiler  should  have  its  own  safety  valve  and  no  stop-valve  should 
be  placed  under  any  condition  between  it  and  the  boiler.  The 
steam  gage  should  be  calibrated  from  time  to  time  with  standard 
gage  or  still  better  by  some  form  of  dead-weight  tester.  It  is 
best  not  to  depend  on  the  water  gage  glass  and  the  gage  cocks 
should  be  used  for  checking  the  water  level  of  a  boiler. 


56  FARM  MOTORS 

In  case  of  low  water  do  not  turn  on  the  feed,  but  shut  the  dam- 
per, cover  the  fuel  bed  with  ashes,  or  if  that  is  not  available 
with  green  coal.  In  case  of  low  water  the  safety  valve  should  not 
be  lifted  until  the  boiler  has  cooled  down,  or  an  explosion  may 
occur. 

A  boiler  should  be  cleaned  often  and  kept  free  from  scale.  If 
clean  water  is  used  a  boiler  may  be  run  several  months  without 
fear  of  serious  scale  formation,  but  in  most  places  boilers  should 
be  cleaned  at  least  once  each  month.  When  preparing  to  clean 
a  boiler  allow  it  to  cool  down,  and  the  water  to  remain  in  the  shell 
until  ready  to  commence  cleaning. 

In  emergencies  split  tubes  may  be  plugged  with  iron  plugs 
without  throwing  the  boiler  out  of  service.  Also  if  a  tube 
becomes  leaky  in  the  tube  sheet  this  can  be  remedied  by  inserting 
a  tapering  sleeve  slightly  larger  than  the  inside  diameter  of  the 
tube. 


CHAPTER  V 

STATIONARY  STEAM  ENGINES 

Description  of  the  Steam  Engine. — A  steam  engine  is  a  motor 
which  utilizes  the  energy  of  steam.  It  consists  essentially  of  a 
piston  and  cylinder  with  valves  to  admit  and  exhaust  steam, 
a  governor  for  regulating  the  speed,  some  lubricating  system 
for  reducing  friction,  and  stuffing  boxes  for  preventing  steam 
leakage. 

In  its  simplest  form,  the  steam  hammer,  the  steam  acting  on 
the  piston  lifts  weights  against  the  force  of  gravity. 


Fig.  49. 

In  the  steam  engine  working  as  a  motor  continuous  rotary 
motion  of  a  shaft  is  essential.  This  is  accomplished  by  the  inter- 
position of  a  mechanism  consisting  of  a  connecting  rod  and  crank, 
which  changes  the  to-and-fro  or  reciprocating  motion  of  the  piston 
into  mechanical  rotation  at  the  shaft.  A  steam  engine  in  which 
the  reciprocating  motion  of  the  piston  is  changed  into  rotary  mo- 
tion at  the  crank  is  called  a  reciprocating  steam  engine  to  differen- 
tiate this  form  of  motor  from  the  steam  turbine  to  be  described 
later. 

57 


58 


FARM  MOTORS 


The  various  parts  of  a  steam  engine  are  illustrated  in  Figs. 
49  and  50. 

Steam  from  the  boiler  at  high  pressure  enters  the  steam  chest 
A,  Fig.  49,  and  is  admitted  through  the  ports  BB  alternately 
to  either  end  of  the  cylinder  by  the  slide  valve  C.  The  same 
valve  also  releases  and  exhausts  the  steam  used  in  pushing  the 
piston  D.  E  is  the  cylinder  in  which  the  steam  is  expanded. 
The  motion  of  the  piston  D,  Fig.  50,  is  transmitted  through  the 
piston  rod  F  to  the  cross-head  G,  and  through  the  connecting 
rod  H  to  the  crank  I  which  is  keyed  to  the  shaft  K. 

The  shaft  is  connected  directly,  or  by  means  of  intermediate 
connectors  such  as  belts  or  chains,  to  the  machines  to  be  driven. 


Fig.  50. 


The  shaft  carries  the  flywheel  L,  the  function  of  which  is  to 
make  the  rate  of  rotation  as  uniform  as  possible  and  to  carry 
the  engine  over  dead  center.  The  dead  center  occurs  when  the 
crank  and  connecting  rod  are  in  a  straight  line  at  either  end 
of  the  stroke,  at  which  time  the  steam  acting  on  the  piston  will 
not  turn  the  crank.  A  flywheel  is  sometimes  used  as  a  driving 
pulley,  as  shown  in  Fig.  51. 

The  eccentric  shown  in  Fig.  51  also  rotates  with  the  shaft.  An 
eccentric  is  a  crank  of  special  form  which  imparts  reciprocating 
motion  to  the  valve  through  the  eccentric  rod  and  valve  stem. 


STATIONARY  STEAM  ENGINES 


59 


The  eccentricity  of  the  eccentric  is  the  distance  between  the 
center  of  the  eccentric  and  the  center  of  the  shaft.  The  travel  of 
the  valve  is  equal  to  the  throw  of  the  eccentric,  or  twice  the  eccen- 
tricity.    Changing  the  eccentricity  changes  the  travel  of  the  valve. 

Stuffing  boxes  which  prevent  the  escape  of  steam  around  the 
rods  are  illustrated  at  M  and  N  in  Figs.  49  and  50. 


'Top  Cylinder- 
HSad 

Cylinder- 
Laofoiinoi 


BoOvm  Cylinder 
Head 


Cross-Head- 
Oiler  BraclKef 


DriYinq 
Pulley^ 


3 

<Sfeann  Chest 
J      Cover 

) 
I   Valve  Stem 
\   SfuifinqBox 

'Nut 

''•Valve  Stem 

Valve  Stem  Bracket 

<--Eccentric 

Rod  Box 
Valve  Stem  Driver 
■Valve  Stsm  Scfuare 


Pillow  Block  Cap 

■Eccentric  Sfrap 
■Eccentric 


Crank  Shalt-- 
Eccentric  Strap 


Fig.  51. 


The  size  of  a  steam  engine  is  given  in  terms  of  the  cylinder 
diameter  and  length  of  stroke  of  the  engine.  Thus  if  an  engine 
is  called  an  8-in.  by  10-in.  engine,  this  means  that  the  diameter 
of  its  cylinder  is  8  in.  and  its  stroke  or  piston  travel  is  10  in. 

Action  of  the  Plain  Slide  Valve. — The  action  of  the  plain  sHde 
valve  will  now  be  taken  up  in  detail,  as  a  thorough  knowledge 
of  this  type  of  valve  will  enable  one  to  understand  all  other  forms. 
Referring  to  Fig.  52  which  shows  a  section  of  a  cylinder  with  the 
slide  valve  in  mid-position,  A  and  B  are  the  steam  ports,  which 
lead  to  the  two  ends  of  the  cylinder;  C  is  the  exhaust  space. 


60 


FARM  MOTORS 


The  steam  ports  are  separated  from  the  exhaust  space  by  the  two 
bridges  D  and  E.  F  is  the  steam  chest.  V  is  a  plain  slide  valve, 
commonly  called  a  D  slide  valve.  The  amount  S  that  the  valve 
V  overlaps  the  outside  edge  of  the  port,  when  in  the  middle  of 
of  its  stroke,  is  called  the  steam  lap.     Similarly  the  amount  by 


Fig.  52. 

which  the  valve  overlaps  the  inside  edge  of  the  port  when  it  is 
in  mid-position  is  called  the  exhaust  lap.  M  and  N  are  the  steam 
and  exhaust  pipes  respectively. 


Fig.  53.  Fig.  54. 

The  four  valve  events  are:  admission,  cut-off,  release  and  com- 
pression. Admission  is  that  point  at  which  the  valve  is  beginning 
to  uncover  the  port,  as  shown  in  Fig.  53.  Cut-off  occurs  (Fig.  54) 
when  the  valve  covers  the  port  preventing  further  admission  of 
steam.     This  is  followed  by  the  expansion  of  the  steam  until  the 


STATIONARY  STEAM  ENGINES 


61 


cylinder  is  communicated  with  the  exhaust  opening,  at  which 
time  release  as  shown  by  Fig.  55  occurs.  Compression  occurs 
when  communication  between  the  cylinder  and  exhaust  opening 
is  interrupted  (Fig.  56)  and  the  steam  remaining  in  the  cylinder 
is  slightly  compressed  by  the  piston.  The  valve  is  in  the  same 
position  at  cut-off  as  it  is  at  admission,  only  it  is  traveling  in  the 
opposite  direction.  Similarly  the  positions  of  the  valve  are  the 
same  at  release  and  compression. 


Fig.  55. 


By  lead  is  meant  the  amount  that  the  port  is  uncovered  when 
the  engine  is  on  either  dead  center.  The  object  of  lead  is  to 
supply  full  pressure  steam  to  the  piston  as  soon  as  it  passes  the 
dead  center. 

If  a  valve  is  constructed  without  laps  as  shown  in  Fig,  57, 
steam  would  be  admitted  to  the  cylinder  at  one  end  or  the  other 
and  exhausted  at  the  opposite  end,  if  the  valve  is  moved  slightly 


Fig.  57. 

in.  either  direction.  This  would  mean  that  steam  admission 
at  one  end  would  take  place  throughout  the  entire  stroke  of  the 
piston  and  would  be  exhausted  from  the  opposite  end  at  the 
same  time.  It  is  evident  that  a  valve  without  laps  will  have 
no  cut-off  and  steam  will  not  be  used  expansively.  To  use  steam 
without  expansion  is  very  uneconomical  and  is  resorted  to  only 
n  direct  acting  steam  pumps.     For  best  economy  a  steam  engine 


62 


FARM  MOTORS 


should  be  provided  with  a  valve  which  cuts  off  at  about  one-third 
of  the  stroke. 

Types  of  Steam-engine  Valve  Gears. — The  simplest  type  of 
valve  for  steam  engines  is  the  single-slide  valve,  which  controls 
the  admission  and  exhaust  of  steam  alternately  to  each  end  of  the 
cylinder.  The  form  shown  in  Fig.  49  is  called  a  piston  valve.  In 
the  position  shown  it  admits  steam  to  the  head  of  the  cylinder, 
the  end  farthest  away  from  crank,  and  at  the  same  time  exhausts 


Fig.  58. 

the  steam  from  the  crank  end  of  the  cylinder.     An  engine  with 
a  piston  valve  is  illustrated  in  Fig.  58. 

Still  a  simpler  type  of  valve,  the  plain  slide  valve,  often  used 
on  portable  and  on  traction  engines,  is  shown  in  Fig.  52.  The 
objection  to  this  type  of  valve  is  that  it  is  not  balanced,  and, 
either  the  friction  of  the  valve  on  its  seat  is  excessive,  or  the  valve 
allows  steam  to  leak  into  the  exhaust  space.  This  is  remedied 
by  the  piston  valve  shown  in  Fig.  49,  which  is  perfectly  balanced, 


STATIONARY  STEAM  ENGINES 


63 


."Balance  Plate 
Steam  Port        /  Steam  .Chesc  Cov-er 


Exhaust  Port 
Steam  Chest 


Counter 
Piston 'Ring 


Fig.  59. 


Fig.  60. 


64 


FARM  MOTORS 


and  by  the  various  forms  of  balanced  slide  valves  illustrated  in 
Figs.  59  and  60  which  work  between  the  valve  seat  and  a  balance 


Fig.  61. 


Fig.  62. 


plate  with  an  accurate  mechanical  fit.  Fig.  61  shows  a  plain 
slide-valve  engine.  An  engine  with  a  balanced  valve  is  illus- 
trated in  Fig.  62. 


STATIONARY  STEAM  ENGINES 


65 


^ — ^f — 5j 


Fig.  63. 


Fig.  64. 


66 


FARM  MOTORS 


A  steam-engine  cylinder  with  separate  steam  valves  and  sepa- 
rate exhaust  valves  is  given  in  Fig.  63,  this  form  of  valve  having 
the  advantage  over  the  single  valve  in  that  the  time  of  exhaust 
can  be  adjusted  independently  of  the  steam  admission. 

In  large  engines  where  high  steam  economy  is  of  great  impor- 
tance the  Corliss  form  of  valve  gear  illustrated  in  Fig.  64  is  used. 
The  wrist  plate  A  is  oscillated  by  an  eccentric  and  transmits  its 
motion  to  the  valve  rods  leading  to  the  levers  which  operate  the 
four  valves  of  the  engine.  The  two  upper  valves  are  the  steam 
valves,  while  the  two  lower  valves  are  the  exhaust  valves.  In 
Fig.  64  one  steam  valve  and  one  exhaust  valve  are  shown  in 


Fig.  65. 


section.  The  exhaust  valves  are  permanently  connected  to  the 
wrist  plate,  while  the  steam  valves  are  provided  with  a  trip 
mechanism  which  releases  the  valve  levers,  thus  closing  the 
valve  rapidly.  Some  forms  of  Corliss  engines  have  both  the 
steam  and  exhaust  valves  permanently  connected  to  wrist  plates ; 
these  types  are  called  non-releasing  Corliss  engines.  The  general 
view  of  a  Corliss  engine  may  be  seen  from  Fig.  65. 

Valve  Setting. — The  object  of  setting  valves  on  an  engine  is  to 
equalize  as  much  as  possible  the  work  done  on  both  ends  of  the 
piston.  A  valve  may  be  set  so  that  both  ends  have  the  same 
lead,  or  so  that  the  point  of  cut-off  is  the  same  at  both  ends. 


STATIONARY  STEAM  ENGINES 


67 


Before  a  valve  can  be  set,  the  dead  centers  for  both  ends  of  the 
engine  must  be  accurately  determined. 

The  method  of  setting  an  engine  on  dead  center  can  best  be 
understood  by  referring  to  Fig.  66.  H  represents  the  engine  cross- 
head  which  moves  between  the  guides  marked  G,  N  is  the  con- 
necting rod,  R  the  crank,  F  the  engine  flywheel,  and  0  a  station- 
ary object. 

To  set  the  engine  on  dead  center,  turn  the  engine  in  the  direc- 
tion in  which  it  is  supposed  to  run,  as  shown  by  the  arrow,  until 
the  cross-head  is  near  the  end  of  its  head  end  travel,  and  make 
a  small  scratch  mark  on  the  cross-head  and  guide  as  at  A.  At 
the  same  time  mark  the  edge  of  the  flywheel  and  the  stationary 
object  opposite  each  other,  as-^t  B.     Turn  the  engine  past  dead 


5 


21 


/mmm/m/////mm/m^^^ 


Fig. 


center,  in  the  same  direction  as  shown  by  the  arrow,  until  the 
mark  on  the  cross-head  and  that  on  the  guide  again  coincide  at  A, 
and  mark  the  flywheel  in  line  with  the  same  point  on  the  station- 
ary object,  obtaining  the  mark  C.  The  distance  between  the 
two  marks  on  the  flywheel  is  now  bisected  at  E.  If  the  mark  E 
on  the  flywheel  is  now  placed  in  line  with  the  mark  on  the  station- 
ary object,  the  engine  will  be  on  the  head  end  dead  center.  Simi- 
larly the  crank  end  dead  center  can  be  found. 

The  stationary  object  may  be  a  wooden  board,  or  a  tram  may 
be  used  with  one  end  resting  on  the  engine  bedplate  and  with 
the  other  end  used  for  locating  the  marks  B,  C,  and  E  on  the 
flywheel. 


68 


FARM  MOTORS 


If  a  valve  is  to  be  set  for  equal  lead  on  both  ends,  set  the 
engine  on  the  dead  center  by  the  method  given  above,  remove 
the  steam  chest  cover,  and  measure  the  lead  at  that  end.  Move 
the  engine  forward  to  the  other  dead  center  and  measure  the  lead 
again.  If  the  lead  on  the  two  ends  is  not  the  same,  correct  the 
difference,  by  moving  the  valve  on  the  valve  stem,  by  moving 
the  eccentric,  or  by  moving  both. 


Fig.  68. 


Fig.  69. 

To  set  an  engine  for  equal  cut-off,  turn  the  engine  until  the 
valve  cuts-off  at  one  end  and  mark  the  position  of  the  cross-head 
on  the  guides.  Then  turn  the  engine  until  cut-off  occurs  on  the 
opposite  end  and  again  mark  this  position  of  the  cross-head  on 
the  guides.     If  the  cut-off  occurs  earlier  at  one  end  than  at  the 


STATIONARY  STEAM  ENGINES  69 

other,  shorten  the  valve  stem  until  the  cut-off  is  equalized  at 
both  ends. 

Steam-engine  Indicator  Cards. — In  general  the  best  method 
of  setting  valves  is  by  means  of  a  steam-engine  indicator,  ex- 
plained in  Chapter  II  and  illustrated  in  Fig.  1.  This  form  of 
instrument  shows  directly  the  action  of  the  steam  inside  the 
engine  cylinder,  recording  the  actual  pressure  at  each  interval  of 
the  stroke. 

An  indicator  card  taken  by  means  of  an  indicator  is  shown  in 
Fig.  67.  The  events  of  stroke  on  the  card  are  marked :  admission 
A,  cut-off  C,  release  R,  compression  K.  Fig.  68  shows  indicator 
cards  taken  from  two  ends  of  a  cylinder  with  a  valve  properly 
set,  while  Fig.  69  shows  indicator  cards  taken  from  an  engine 
where  the  valve  is  poorly  set. 

Classification  of  Steam  Engines. — Steam  engines  are  classified 
according  to  the  type  of  valve  gear  used  into : 

1.  Plain  slide  or  piston  valve  engines  with  throttling  governor. 

2.  Automatic  high-speed  engines.  Under  this  head  are  in- 
cluded engines  using  piston  valves  or  some  form  of  balanced 
slide  valve  with  flywheel  governor. 

3.  Corliss  slow-speed  engines.  Under  this  classification  are 
included  Corliss  or  other  engines  which  are  arranged  with 
releasing  steam  valves,  and  which  operate  at  a  speed  of  150 
revolutions  per  minute  or  less.  This  type  of  valve  gear  is 
sometimes  called  the  ''drop  cut-off"  gear. 

4.  Corliss  high-speed  engines,  which  have  non-releasing  valves 
and  operate  at  a  speed  of  200  r.p.m.  or  more. 

5.  Poppet  valve  engines. 

Adaptability  of  Various  Types  of  Steam  Engines. — The  plain 
shde  valve  engines  are  simple  in  construction,  but  are  very  un- 
economical in  the  use  of  steam.  They  are  still  used  to  some 
extent  in  out-of-the-way  places  where  facilities  for  repairing  are 
poor,  but  are  being  replaced  for  most  purposes  by  the  automatic 
engines  either  with  a  piston  valve  or  with  a  balanced  slide 
valve.  The  cost  of  an  automatic  engine  is  not  much  greater 
than  that  of  the  plain  slide  valve  engine  and  for  powers  up  to 
200  h.p.  this  type  of  engine  is  very  desirable.  For  larger  powers 
some  form  of  Corliss  engine  or  Poppet  valve  engine  may  be  found 
more  satisfactory.    . 


70  FARM  MOTORS 

Condensing  and  Non-condensing  Engines. — Another  method 
of  classifying  engines  is  into : 

1.  Condensing  engines. 

2.  Non-condensing  engines. 

In  case  of  the  condensing  engine  the  exhaust  steam  from  the 
engine  cylinder  escapes  into  a  condenser,  where  it  is  cooled  and 
condensed  into  water,  thus  reducing  the  back  pressure  and 
producing  a  vacuum. 

In  the  case  of  non-condensing  engines  the  exhaust  steam 
escapes  into  the  atmosphere,  or  into  heating  coils,  where  it  is 
utilized  in  heating  buildings.  The  pressure  of  the  exhaust 
steam  in  the  case  of  the  non-condensing  engine  exceeds  atmos- 
pheric pressure. 

Generally  a  condensing  engine  will  use  about  25  per  cent,  less 
steam  than  a  non-condensing  engine  of  the  same  size  on  account 
of  the  lower  back  pressure.  Small  engines  are  very  seldom 
operated  condensing,  as  the  gain  in  economy  is  usually  more 
than  balanced  by  the  increased  first  cost  of  the  equipment  and 
by  the  greater  complications  of  the  power  plant. 

Losses  in  Steam  Engines. — The  main  losses  in  a  steam 
engine  are : 

1.  Loss  in  pressure  as  the  steam  is  transferred  from  the 
steam  boiler  to  the  engine  cylinder  due  to  the  throttling  action 
in  the  steam  pipe  and  ports. 

2.  Leakage  past  piston  and  valve. 

3.  Losses  due  to  the  condensation  of  steam  in  the  cylinder 
during  part  of  the  stroke. 

4.  Radiation  losses  which  take  place  when  the  steam  passes 
through  the  steam  pipes  from  the  boiler  to  the  cylinder  and  also 
while  the  steam  is  in  the  cylinder. 

5.  Losses  of  heat  in  the  exhaust  steam. 

6.  Mechanical  losses  due  to  the  friction  of  the  moving  parts. 
Of  the  above  losses  those  due  to  the  heat  carried  away  in  the 

exhaust  steam  are  greatest  and  are  usually  75  per  cent,  or  more  of 
the  heat  supplied  in  the  steam.  Part  of  this  heat  can  be  used 
for  siich  purposes  as  the  heating  of  feed  water  before  it  enters 
the  boiler,  for  heating  buildings,  or  in  using  the  exhaust  steam  in 
connection  with  various  manufacturing  processes. 

The  other  great  loss  is  that  due  to  the  condensation  of  steam 


STATIONARY  STEAM  ENGINES 


71 


which  takes  place  when  the  entering  steam  comes  in  contacjt^ 
with  the  cylinder  walls  which  are  at  the  temperature  of  the  ex- 
haust steam.  This  loss  can  be  reduced  to  a  considerable  extent 
by  having  the  steam  entering  the  cylinder  as  dry  as  possible. 
Another  method  for  reducing  this  loss,  which  is  used  in  connec- 
tion with  large  engines,  is  to  compound  the  engine. 


Fig.  70. 


By  compounding  is  meant  the  sub-division  of  the  expansion 
of  the  steam  into  two  or  more  cylinders.  The  steam  on  leaving 
the  boiler  enters  the  high-pressure  cylinder,  is  partly  expanded 
and  then  enters  one  or  more  cylinders  where  its  expansion  is 
completed  to  the  exhaust  pressure.     The  range  of  pressures  in 


72 


FARM  MOTORS 


each  cylinder  of  a  compound  engine  being  less  than  is  the  case 
of  a  simple,  or  one-cylinder  engine,  the  temperature  difference 
between  the  incoming  and  outgoing  steam  is  less.  This  lower 
temperature  range  decreases  the  condensation  of  the  steam  in 
the  cylinder.  The  gain  in  economy  does  not  compensate  for 
the  increase  first  cost  of  compound  engines  as  compared  with 
simple  engines  in  sizes  under  200  h.p.  A  compound  engine  is 
illustrated  in  Fig.  70. 


Fig.  71. 


Radiation  losses  in  the  steam  pipes  leading  from  the  boilers 
to  the  engines  can  be  reduced  to  a  minimum  by  covering  the 
pipes.  A  good  pipe  covering  will  save  the  latent  heat  in  the 
steam  that  would  otherwise  be  lost,  will  keep  the  steam  drier 
and  will  pay  for  itself  in  a  very  short  amount  of  time. 

The  cylinders  of  most  steam  engines  are  now  jacketed  with 
some  good  non-conductor  of  heat  and  this  loss  is  very  small. 

Mechanical  losses  in  steam  engines  can  be  reduced  by  proper 
lubrication.     Oil  can  be  applied  to  the  various  parts  by  separate 


STATIONARY  STEAM  ENGINES 


73 


sight-feed  lubricators  and  grease  cups.  Another  method,  illus- 
trated in  Fig-.  71,  is  to  connect  an  oil  tank  conveniently  located- 
with  the  various  parts  by  adjustable  sight-feed  tubes,  allowing 
different  rates  of  feed  to  the  various  bearings.  Still  another 
method  is  to  enclose  some  of  the  parts  and  make  them  self-oiling. 
The  losses  due  to  leakage  past  the  piston  and  valves  are  usually 
very  small  in  well  designed  engines  with  balanced  Corliss  or 
Poppet  valves.  The  various  forms  of  balanced  slide  valves  can 
be  kept  tight  by  means  of  balance  plates. 


Fig.  72. 


Steam-engine  Governors. — The  function  of  a  governor  is  to 
control  the  speed  of  rotation  of  a  motor  irrespective  of  the  power 
which  it  develops.  In  the  steam  engine,  the  governor  maintains 
a  uniform  speed  of  rotation  either  by  varying  the  initial  pressure 
of  the  steam  supplied,  or  by  changing  the  point  of  cut-off  and 
hence  the  portion  of  the  stroke  during  which  steam  is  admitted. 

Governors  which  regulate  the  speed  of  an  engine  by  varying 
the  initial  pressure  of  the  steam  supplied  to  the  engine  are  called 


74 


FARM  MOTORS 


Fig.  73. 


Fig.  74. 


STATIONARY  STEAM  ENGINES 


75 


throttling  governors.  This  is  the  simplest  form  of  governor  and 
is  used  mainly  on  engines  of  the  plain  slide-value  type.  The 
external  appearance  of  a  governor  of  this  type  is  illustrated  in  Fig. 
61.  In  Fig.  72  is  given  a  section  of  a  throttling  governor,  showing 
details.  This  form  of  governor  is  attached  to  the  steam  pipe 
at  A  and  is  connected  to  the  engine  cylinder  at  B,  so  that  the 
steam  must  pass  the  valve  V  before  entering  the  engine.  The 
valve  V  is  a  balanced  valve  and  is  attached  to  a  valve  stem  S, 


Yoke  Pin- 
Hole  for  loadinq  with 
Shot     ^ 
Connecting  Arm  Pins'  _, 
Ho/e  for  removing  Shot-' 
-Steam  Brackets^,  ^^^^^^  Weight  Ball  Bearing. 
Link  Collar  Pin- 
Spindle  Sleeve 


6ov.  Da5h  Pot  Brass 
Head 
governor  SafetyStop. 
OY  Dash  PotRod-j^ 
'ov.  Brass 
Head; 


SafetyCaml 
Knock  off  Cam 


Small  (bOY.  Pulley-. 


Spindle  Top 

''endulumArm 
Yokes 

Center  Weight 
vdulumArm 
Connecting  Arm 

Ball 

,■  Drop  Rod  Brass 
'■       Head 
-Link  Collar 
rSpindle  Ball 
■  Bearing 

Spindle 

dovernorDrop 
Rod  ^ 
Drop  Rod 
'      Arm 


6oY.Dash  Pof  Cover-. 
Gov  Dash  Pot  ^ 
Dash  Pot  Plunger -"^ 
Adjusting  Plate-' 
Babbit- 


BellCrank 
Bearing 

\BellCmnkShaPt 

\  'Governor  Column 

-Spindle 

'Babbit 

6 ov  Stand 
Support 

Mitre  Oears 


Pulley  Shaft 


Fig.  75. 


at  the  upper  end  of  which  are  two  balls  C  C.  The  valve  stem 
and  balls  are  driven  from  the  engine  shaft  by  a  belt,  which  is 
connected  to  the  pulley  P,  and  which  in  turn  runs  the  bevel 
gears  D  and  E.  As  the  speed  of  the  engine  is  increased  the 
centrifugal  force  makes  the  balls  fly  out,  and  in  doing  so  they 
force  down  the  valve  stem  S,  thus  reducing  t  he  area  of  the  open- 
ing through  the  valve,  and  the  steam  to  the  engine  is  throttled. 


76 


FARM  MOTORS 

O   cQ)      [ft 


Fig.  78 


STATIONARY  STEAM  ENGINES 


77 


As  soon  as  the  engine  begins  to  slow  down,  the  balls  increase  thtr  ~ 
steam  opening  through  the  valve  V.     The  speed  at  which  the 
steam  is  throttled  can  be  changed  within  certain  limits  by  regu- 
lating the  position  of  the  balls  by  means  of  the  nut  N. 

Most  of  the  better  engines  are  governed  by  varying  the  point 
of  cut-off  and  hence  the  total  volume  of  steam  suppHed  to  the 
cylinder. 


Fig.  79. 


In  high-speed  automatic  engines  this  is  accomplished  by  some 
form  of  flywheel  governor  which  is  usually  placed  on  the  engine 
shaft,  and  which  controls  the  point  of  cut-off  by  changing  the 
position  of  the  eccentric.     Figs.  73  and  74  show  two  forms  of 


Fig.  80. 

flywheel  governors.     As  the  speed  of  the  engine  increases,  the 
governor    weights   are   thrown   outward   by   centrifugal   force, 
moving  the  eccentric  by  means  of  levers  and  thus  changing  the 
time  during  which  steam  is  admitted  into  the  engine  cylinder. 
The  general  construction  of  governors  for  Corliss  engines  is 


78 


FARM  MOTORS 


illustrated  in  Fig.  75.  As  the  speed  of  the  engine  increases  the 
balls  B  B,  which  are  driven  from  the  engine  shaft  by  a  belt  which 
is  connected  to  the  small  governor  pulley  P,  fly  out  moving  the 
bell  crank  lever  L,  which  in  turn  changes  the  position  of  the 
knock-off  cam,  unlatching  the  gear  and  releasing  the  valve. 


uSS^Sjftt 


Fig.  81. 

Engine  Details. — The  general  construction  of  steam-engine 
cylinders  can  be  seen  from  the  previous  illustrations.  A  section 
through  a  cylinder  of  a  Corliss  engine,  showing  valves,  is  shown 
in  Fig.  76.  Steam-engine  cylinders  are  made  of  cast  iron.  As 
the  cylinder  wears  it  has  to  be  rebored  so  as  to  maintain  true 
inside  surfaces.  The  thickness  of  the  cylinder  walls  should  not 
only  be  strong  enough  safely  to  withstand  the  maximum  steam 


Fig.  82. 

pressure,  but  should  allow  for  reboring.  All  steam-engine 
cylinders  should  be  provided  with  drip  cocks  at  each  end  in 
order  to  drain  the  cylinder  and  steam  chest  when  starting. 

A  good  piston  should  be  steam  tight  and  at  the  same  time 
should  not  produce  too  much  friction  when  sliding  inside  of  the 


STATIONARY  STEAM  ENGINES 


79 


engine  cylinder.  The  piston  is  usually  constructed  somewhat 
smaller  than  the  inside  diameter  of  the  engine  cylinder,  and  is 
made  tight  by  the  use  of  split  cast  iron  packing  rings.     In  Fig. 


Fig.  83. 

77  is  illustrated  a  piston  with  its  packing  rings  leaning  against 
the  piston  rod;  also  a  piston  with  the  rings  in  place. 

The  general  construction  of  steam-engine  cross-heads  is  illus- 


FiG.  84. 


trated  in  Figs.  78  and  79.  All  cross-heads  should  be  provided 
with  shoes  which  can  be  adjusted  for  wear.  The  method  of 
accompHshing  this  is  illustrated  in  Fig.  79. 

Figure  80  shows  a  connecting  rod.     It  is  connected  at  one  end 


80 


FARM  MOTORS 


with  the  cross-head  and  at  the  other  with  the  crank-pin.  A  con- 
necting rod  should  be  so  constructed  that  the  wear  on  its  bearings 
can  be  taken  up.  This  is  usually  accomplished  by  wedges  and 
set-screws  as  illustrated. 

The  construction  of  several  types  of  cranks  can  be  seen  from 
Figs.  58  and  70.  Some  engines  have  their  cranks  located  between 
the  two  'bearings  of  an  engine,  and  are  called  center  crank 
engines.  Engines  which  have  the  cranks  located  at  the  end  of 
the  shaft  and  on  one  side  of  the  two  bearings  are  called  side-crank 
engines. 


Fig.  87. 


The  eccentric  is  a  special  form  of  crank.  It  is  usually  set 
somewhat  more  than  90  degrees  ahead  of  the  crank  and  gives 
motion  to  the  valve  or  valves  in  the  steam  chest  of  the  engine. 
The  eccentric  is  a  cast-iron  disc  through  which  the  shaft  passes 
and  which  gives  motion  to  the  valve.  Fig.  81  shows  an  eccentric 
rod  and  strap. 

The  main  bearings  of  steam  engines  are  illustrated  in  Figs.  82 
and  83.     These  bearings  are  usually  made  in  three  or  four  parts 


STATIONARY  STEAM  ENGINES 


81 


and  can  be  adjusted  for  wear  by  means  of  wedges  and  set  screws 
fastened  with  lock-nuts. 

Engine  Auxiliaries. — Under  this  head  will  be  explained 
lubricators,  steam  separators,  exhaust-pipe  heads  and  condensers. 
Other  engine  auxiliaries  are  treated  in  other  parts  of  the  book. 


^ 


Fig.  88. 


Lubricators. — The  subject  of  lubricating  the  moving  parts  of 
an  engine  was  treated  to  some  extent  in  connection  with  the 
discussion  of  mechanical  losses  in  steam  engines. 


Bearings  may  be  lubricated  by  grease  cups  illustrated  by 
Figs.  84  and  85.  The  first  type  is  used  on  stationary  bearings, 
the  grease  being  forced  out  by  screwing  the  cap  down  by  hand. 
The  type  illustrated  in  Fig.  85  is  automatically  operated,  and  is 
used  for  the  lubrication  of  crank  pins. 


82 


FARM  MOTORS 


If  oil  is  used,  a  plain  oil  cup  illustrated  in  Fig.  86  can  be  em- 
ployed, or  some  form  of  sight-feed  lubricator,  as  shown  in  Fig. 
87.  By  means  of  the  sight-feed  types  the  flow  of  oil  can  be 
regulated  and  the  drops  of  oil  issuing  from  the  lubricator  can 
be  seen. 

For  the  lubrication  of  steam-engine  cylinders  some  form  of 
sight-feed  automatic  steam  lubricator,  as  illustrated  in  Fig.  88, 
should  be  employed.  This  form  of  lubricator  is  used  to  introduce 
a  heavy  oil  into  the  steam  entering  the  cylinder.     This  oil  is  a 


specially  refined  heavy  petroleum  oil  which  will  neither  decom- 
pose, vaporize  or  burn  when  exposed  to  the  high  temperature  of 
steam.  Steam  from  the  pipe  leading  to  the  cylinder  B  is  admitted 
through  the  pipe  F  to  the  condensing  chamber  E  where  it  is  con- 
densed and  falls  through  the  pipe  P  to  the  bottom  of  the  chamber 
A.  The  oil  which  is  contained  in  chamber  A  rises  to  the  top, 
is  forced  through  the  tube  S,  ascends  in  drops  through  the 
water  in  the  gage  glass  H,  and  into  the  steam  pipe  K  leading  to 
the  steam  chest.     The  amount  of  oil  fed  is  regulated  by  the 


STATIONARY  STEAM  ENGINES 


83 


needle  valve  G.     T  shows  the  amount  of  oil  in  the  chamber-A^ 
In  order  to  fill  the  chamber  A,  the  valves  on  the  pipes  F  and 
H  are  closed,  the  water  is  drained  out  through  G.  and  the  cap 
D  is  removed  for  receiving  the  oil. 

Figure  89  shows  a  hand  oil  pump  which  is  sometimes  used  to 
admit  oil  into  the  cylinder  of  an  engine  when  starting. 

Steam  Separators. — The  function  of  a  steam  separator  is  to 
remove  any  water  which  may  be  contained  in  the  steam  before 
it  enters  the  engine  cylinder.  A  separator  placed  in  the  exhaust 
pipe  of  an  engine  will  remove  a  large  part  of  the  oil,  making  the 


Fig.  92. 


exhaust  steam  more  suitable  for  heating,  manufacturing  purposes, 
or  for  use  in  steam  boilers  after  condensation. 

The  importance  of  having  the  steam  entering  the  engine 
cylinder  as  dry  as  possible  was  explained  in  an  earlier  part  of 
this  chapter.  A  good  steam  separator,  if  of  sufficient  size,  will 
insure  fairly  dry  steam  and  should  be  used  in  connection  with 
all  stationary  steam  engines. 

Figure  90  shows  in  section  one  form  of  steam  separator.  The 
wet  steam  enters  at  A,  strikes  the  deflecting  plates,  its  velocity 
is  decreased  and  the  entrained  water,  which  is  heavier  than  the 


84 


FARM  MOTORS 


steam,  falls  to  the  bottom  and  is  removed  at  C  by  means  of 
trap.     The  dry  steam  passes  out  at  B. 


Fig.  93. 


Reo/ulaft'nof 
Choim  Wheel 


Injecfioin- 
Wafer  Inlet 


Sect! ma > 

Spray  ripe 


To  Air  Pump 


^Barometric 
Leg  Connection 


Fig.  94 


Exhaust  Pipe  Heads. — The  function  of  an  exhaust  pipe  head 
is  to  prevent  the  discharge  of  oil  and  water  from  exhaust  pipes 


STATIONARY  STEAM  ENGINES  85 

of  steam  engines.  The  discharge  of  oil  and  water  from  an  un-. 
protected  pipe  will  disfigure  buildings,  will  reduce  the  life  of  power- 
house roofs  and  in  the  winter  time  it  is  a  nuisance  on  account  of 
the  accumulation  of  ice  upon  the  buildings  and  pavement  due 
to  the  escape  of  water.  The  principle  of  an  exhaust  head  is 
illustrated  in  Fig.  91.  The  exhaust  pipe  is  connected  at  A. 
The  steam  is  hurled  against  the  inverted  cone  and  its  direction 
is  changed,  the  dry  steam  escaping  at  B,  while  the  heavier  water 
and  oil  are  di charged  through  the  pipe  C. 

Condensers. — Condensers  for  the  use  in  connection  with 
steam  engines  are  divided  into  two  types,  known  as  the  surface 
and  direct-contact  or  jet  condenser. 

The  details  of  construction  of  the  surface  condenser  are 
illustrated  in  Figs.  92  and  93.  Fig.  92  shows  a  surface  condenser 
with  one  of  the  heads  removed.  The  various  auxiliaries  of  the 
surface  condenser  are  illustrated  in  Fig.  93.  The  cooling  water 
is  forced  through  the  tubes  of  the  condenser  by  the  circulating 
pump  and  condenses  the  steam  in  contact  with  the  other  side  of 
the  tubes.  The  steam  enters  the  condenser  at  the  exhaust 
inlet  and  is  drawn  off  by  a  vacuum  pump,  often  called  an  air 
pump.  In  the  figure  both  the  circulating  and  air  pumps  are 
driven  by  one  steam  cylinder. 

The  jet  condenser  differs  from  the  surface  types  in  that  the 
steam  comes  in  direct  contact  with  the  water  by  which  it  is 
condensed.  One  form  of  jet  condenser  is  illustrated  in  Fig.  94. 
The  exhaust  steam  from  the  engine  enters  at  E  and  is  con- 
densed by  coming  in  contact  with  the  water  entering  at.W.  The 
condensed  steam  goes  out  at  B,  while  A  is  connected  to  an  air 
pump  for  the  removal  of  any  air  which  might  enter  the  condenser 
with  the  steam  or  with  the  condensing  water. 

The  jet  condenser  is  much  simpler  than  the  surface  condenser. 
The  surface  condenser  has  the  advantage  in  that  its  cooling 
water  does  not  come  in  direct  contact  with  the  steam  to  be  con- 
densed. For  this  reason  surface  condensers  are  used  where  the 
condensed  steam  is  returned  to  the  boiler,  and  where  the  cooling 
water  is  salty,  muddy  or  otherwise  unfit  for  steam  making. 

Steam  Turbines. — The  steam  turbine  differs  from  the  steam 
engine  described,  in  that  it  produces  rotary  motion  directly  and 
without  any  reciprocating  parts.     It  consists  of  a  stationary 


86 


FARM  MOTORS 


part  and  one  or  more  wheels  with  vanes  which  are  rotated  by- 
steam  striking  the  vanes.  The  elastic  force  of  the  steam,  instead 
of  acting  on  a  piston,  is  exerted  on  the  steam  itself,  producing  a 
drop  in  pressure  and  a  steam  jet  of  high  velocity. 


Fig.  95. 

The  steam  turbine  is  best  adapted  for  the  driving  of  elec- 
trical generators,  centrifugal  pumps  and  air  compressors,  cream 
separators  and  other  machinery  requiring  a  high-speed  rotation. 

In  large  sizes  the  steam  turbine  is  somewhat  more  economical 
than  the  reciprocating  steam  engine  and  occupies  considerably 
less  space.  The  steam  turbine  requires  no  internal  lubrication, 
and  thus  the  exhaust  steam  can  be  used  again  in  the  boiler  with- 
out requiring  oil  filtration.  For  large  power  plants  the  steam 
turbine  has  several  other  advantages. 

While  there  are  a  great  many  makes  of  turbines,  they  vary 
only  in  minor  details,  and  belong  to  either  the  impulse  type  or 


STATIONARY    STEAM  ENGINES 


87 


the  reaction  type.  In  the  impulse  type  the  steam  expands  only. 
in  stationary  nozzles,  while  in  the  reaction  type  part  of  the  ex- 
pansion takes  place  in  stationary  vanes  and  part  in  the  vanes  of 
the  rotating  wheels. 

The  action  of  one  form  of  impulse  steam  turbine  much  used  for 
the  driving  of  cream  separators  is  illustrated  in  Fig.  95.     A,  B,  C 


Fig.  96. 


and  D  are  stationary  nozzles  in  which  the  steam  is  completely 
expanded  and  strikes  the  vanes  V,  giving  a  direct  rotary  motion 
to  the  wheel  W  and  also  to  the  shaft  S. 

The  application  of  this  type  of  steam  turbine  to  the  driving  of 
a  cream  separator  is  illustrated  in  Fig.  96. 


88 


FARM  MOTORS 


Installation  and  Care  of  Steam  Engines. — Foundations  for 
steam  engines  are  usually  put  in  by  the  purchaser,  the  manu- 
facturer furnishing  complete  drawings  for  that  purpose.  Draw- 
ings of  a  board  template  are  also  included.  A  template  is  a 
wooden  frame  which  is  used  in  locating  the  foundation  bolts  and 
for  holding  them  in  position  while  building  the  foundation.        • 

Before  starting  on  the  foundation  a  bed  should  be  prepared 
for  receiving  it.  The  depth  of  bed  depends  on  the  soil.  If  the 
soil  is  rocky  and  firm,  the  foundation  can  be  built  without  much 
difficulty.  When  the  soil  is  very  soft  piles  may  have  to  be 
driven.  The  piles  should  be  excavated  to  a  depth  of  about  two 
feet  and  the  space  filled  with  concrete. 


Fig.  97. 


The  wooden  template  is  then  constructed  from  the  drawings 
holes  being  bored  for  the  insertion  of  foundation  bolts. 

Foundations  may  be  built  of  brick  or  of  concrete.  If  of  con- 
crete the  mixture  should  consist  of  one  part  of  cement,  two 
parts  of  sharp  sand  and  four  parts  of  crushed  stone.  The  stone 
should  be  of  a  size  as  will  pass  through  a  2-in.  ring.  In  starting 
on  a  concrete  foundation,  a  wooden  frame  of  the  exact  shape  of 
the  foundation  is  built.  This  template  is  then  placed  in  position 
in  the  manner  shown  by  Fig.  97,  and  the  bolts  are  put  in,  the 
heads  of  the  bolts  being  at  the  bottom  in  recesses  of  cast-iron 
anchor  plates  marked  P.  Often  the  foundation  bolts  are 
threaded  at  both  ends  and  the  anchor  plates  are  held  in  place  by 
square  nuts.  A  piece  of  galvanized  iron  pipe  should  be  placed 
around  each  bolt,  so  as  to  allow  the  bolts  to  be  moved  slightly 


STATIONARY  STEAM  ENGINES  89 

to  pass  through  the  holes  in  the  engine  bedplate,  in  case_  an 
error  should  occur  in  the  placing  of  the  bolts,  or  in  the  location 
of  the  bolt  holes  in  the  engine  bedplate. 

With  the  frame,  template  and  foundation  bolts  in  place,  the 
concrete  can  now  be  poured  and  tamped  down.  After  the  con- 
crete has  set  the  template  is  removed  and  the  foundation  is  made 
perfectly  level.  It  is  well  to  allow  a  concrete  foundation  to  set 
several  weeks  before  placing  any  weight  on  it. 

When  the  foundation  is  ready,  the  engine  is  placed  in  position 
and  leveled  by  means  of  wedges.  The  nuts  on  the  bolts  are  now 
screwed  down  and  the  engine  is  grouted  in  place  by  means  of 
neat  cement,  this  serving  to  fill  any  crevices  and  to  give  the 
engine  a  perfect  bearing  on  the  foundation. 

After  erecting  the  engine  and  all  its  auxiliaries,  including  pipes, 
valves,  cocks  and  lubricators,  all  the  parts  should  be  carefully 
examined  and  cleaned,  and  a  coating  of  oil  should  be  applied  to 
all  rubbing  surfaces,  cylinder  oil  being  used  for  the  wearing 
parts  in  the  valve  chest  and  cylinder. 

Before  the  engine  is  operated  for  the  first  time,  it  is  well  to 
loosen  the  nuts  and  bolts,  adjust  bearings,  and  turn  the  engine 
over  slowly  until  an  opportunity  has  been  given  for  any  in- 
equalities due  to  tool  and  file  marks  to  be  partially  eliminated, 
and  also  to  prevent  heating  that  might  occur  if  there  was  an 
error  in  adjustment. 

When  the  engine  is  ready  to  start,  the  boiler  valve  should  be 
slowly  opened  to  allow  the  piping  to  warm  up,  but  leaving  the 
drain  cock  in  the  steam  pipe,  above  the  steam  chest,  open  to 
permit  the  escape  of  condensation.  While  the  piping  is  being 
warmed  up  all  the  grease  cups  and  lubricators  are  filled.  Before 
opening  the  throttle  valve,  all  cylinder  and  steam  chest  drain 
cocks  should  be  opened  to  expell  water,  and  the  flow  or  oil  started 
through  the  various  lubricators.  The  throttle  valve  is  then 
opened  gradually,  and  both  ends  of  the  engine  warmed  up. 
This  in  the  case  of  a  single-valve  engine  can  be  accomplished  by 
turning  over  the  engine  slowly  by  hand  to  admit  steam  in  turn 
to  each  end  of  the  cylinder.  In  starting  a  Corliss  engine  the 
eccentric  is  unlocked  from  the  pin  on  the  wrist  plate  and  the 
wrist  plate  is  rocked  by  hand  sufficiently  to  allow  steam  to  pass 
through  each  set  of  valves.     The  drain  cocks  are  closed  soon 


90  FARM  MOTORS 

after  the  throttle  is  wide  open  and  the  engine  up  to  speed,  provid- 
ing steam  is  blowing  through. 

When  stopping  an  engine,  close  the  throttle  valve.  As  soon 
as  engine  stops,  close  the  lubricators,  wipe  clean  the  various 
parts,  examining  all  bearings  and  leaving  engine  in  perfect  con- 
dition ready  to  start. 

The  above  instructions  apply  to  non-condensing  engines. 
If  the  engine  is  to  be  operated  condensing,  the  circulating  and 
air  pumps  should  be  started  while  the  engine  is  warming  up. 
The  other  directions  apply  with  slight  modifications  to  all  types 
of  steam  engines. 

In  regard  to  daily  operation,  cleanliness  is  of  great  importance. 
No  part  of  the  engine  should  be  allowed  to  become  dirty  and  all 
parts  must  be  kept  free  from  rust.  It  is  well  to  draw  off  all  the 
oil  from  bearings  quite  frequently  and  to  clean  them  with 
kerosene  before  refilling  with  fresh  oil.  In  starting  it  .is  well  to 
give  the  various  parts  plenty  of  oil,  but  the  amount  should  be 
decreased  as  the  engine  warms  up. 

Competent  engineers  usually  make  a  practice  of  going  over 
and  cleaning  every  bearing,  nut,  and  bolt,  immediately  on  shut- 
ting down.  This  practice  not  only  keeps  the  engine  in  first-class 
condition,  as  regards  cleanliness,  but  enables  the  operator  to 
detect  the  first  indication  of  any  defect  that,  if  overlooked, 
might  result  seriously. 

If  a  knock  develops  in  a  steam  engine,  it  should  be  located 
and  remedied  at  once.  Knocking  is  usually  due  to  lost  motion 
in  bearings,  worn  journals  or  cross-head  shoes,  water  in  the 
cylinder,  loose  piston  or  to  poor  valve  setting.  Locating 
knocks  in  steam  engines  is  to  a  great  extent  a  matter  of  experi- 
ence and  no  definite  rules  can  be  laid  down  which  will  meet  all 
cases. 

However,  the  beginner  may,  by  careful  attention  to  the 
machine,  learn  to  trace  out  the  location  of  a  knock  in  a  com- 
paratively short  time.  He  must,  however,  bear  in  mind 
that  he  cannot  rely  on  his  ear  for  locating  it,  as  the  sound 
produced  by  a  knock  is,  in  many  cases,  transmitted  along  the 
moving  parts,  and  apparently  comes  from  an  entirely  different 
point. 

A  knock,  due  to  water  in  the  cylinder,  is  usually  sharp  and 


STATIONARY  STEAM  ENGINES  91 

crackling  in  its  nature,  while  that  in  the  case  of  a  crank  or  a  cross^_ 
head  pin  is  more  in  the  nature  of  a  thud.  If  the  knock  should  be 
due  to  looseness  of  the  main  bearings,  the  location  may  be  de- 
tected by  carefully  watching  the  flywheel,  while  if  the  cross- 
heads  are  loose  in  the  guides  the  observer  may  be  able  to  detect 
a  motion  crossways  of  the  cross-head,  but  it  is  not  Hkely  that  he 
can  do  this  with  accuracy  in  the  case  of  a  high-speed  engine,  and 
the  cross-head  should  be  tested  when  the  engine  is  at  rest.  In 
no  case  should  any  adjustments  he  made  in  hearings  or  moving  parts 
of  an  engine  unless  the  machine  is  at  standstill  or  heing  turned  hy 
hand;  never  when  under  its  own  power. 

The  heating  of  a  bearing  is  always  due  to  one  of  five  causes : 

1.  Insufficient  lubrication  due  to  insufficient  quantity  of  oil, 
wrong  kind  of  oil,  or  lack  of  proper  means  to  distribute  the  oil 
about  the  bearings. 

2.  The  presence  of  dirt  in  the  bearings. 

3.  Bearings  out  of  alignment. 

4.  Bearings  improperly  adjusted;  they  may  be  either  too 
tight  or  too  loose. 

5.  Operation  in  a  place  where  the  temperature  is  excessive. 

In  case  a  bearing  should  run  hot  and  it  is  very  undesirable  to 
shut  down,  it  is  oftentimes  possible  to  keep  going  by  a  liberal 
application  of  cold  water  through  the  entire  heating  surface  or 
surfaces.  It  is  sometimes  possible  to  stop  heating  by  changing 
from  machine  oil  to  cylinder  oil  which  has  a  higher  flash  point. 

Should  a  bearing,  particularly  a  large  one,  be  overheated  to 
the  extent  that  it  is  necessary  to  shut  down  the  engine,  do  not 
shut  down  suddenly  or  allow  the  bearing  to  stand  any  length  of 
time  without  attention.  This  is  particularly  important  in  the 
case  of  babbitted  bearings,  as  the  softer  metal  of  the  bearings 
will  tend  to  become  brazed  to,  or  fused  with,  the  harder  metal 
of  the  shaft,  and  it  may  be  necessary  to  put  the  engine  through 
the  shop  before  it  can  be  used  again. 

In  case  of  the  necessity  of  shutting  down  for  a  hot  bearing, 
first  remove  the  load,  then  permit  the  engine  to  revolve  slowly 
under  its  own  steam  until  the  bearing  is  sufficiently  cool  to  per- 
mit the  bare  hand  to  rest  on  it,  or  until  the  box  can  be  loosened 
sufficiently  to  remove  the  soft  metal  of  the  bearing  from  close 
contact  from  the  shaft. 


92  FARM  MOTORS 

The  presence  of  water  in  the  cylinder  is  always  a  source  of 
danger,  and  care  should  be  taken  that  the  water  of  condensation 
is  thoroughly  drained  from  the  cylinder  when  the  engine  is  first 
started,  at  shutting  down,  and  at  regular  intervals  throughout 
the  operation.  An  accumulation  of  water  may  readily  result 
in  the  blowing  out  of  a  cylinder  head  with  its  resultant  loss  to 
property  and  possibly  of  life.  There  are  several  appliances  now 
on  the  market  which  automatically  safeguard  the  cylinder  head 
by  providing  a  weak  point  in  the  drain  system  which  will  relieve 
the  excess  pressure  before  the  cylinder  head  gives  way. 


CHAPTER  VI 

GAS  AND  OIL  ENGINES 

The  Internal  Combustion  Engine. — The  internal  combustion 
engine,  commonly  called  a  gas  engine,  differs  from  the  steam 
engine,  in  that  the  transformation  of  the  heat  energy  of  the  fuel 
into  work  takes  place  within  the  engine  cylinder.  The  fuel  may 
be  gasoline,  kerosene,  crude  petroleum,  alcohol,  illuminating 
gas,  or  some  form  of  power  gas. 

In  order  to  form  an  explosive  mixture  in  the  cylinder,  air  must 
be  mixed  in  certain  proportions  with  the  fuel,  and  this  can  only 
be  accomplished  when  the  fuel  is  in  the  gaseous  state,  or  is  a  mist 
of  liquid  fuel  easily  vaporized  at  ordinary  temperatures.  Thus 
the  essential  difference  between  internal  combustion  engines  using 
the  various  fuels  is  in  the  construction  of  the  device  for  preparing 
the  fuel  before  it  enters  the  engine  cylinder.  If  the  fuel  is  a  gas, 
only  a  stop  valve  is  necessary  between  the  source  and  the  gas 
engine  admission  valve.  The  device  for  preparing  liquid  fuels 
depends  on  the  character  of  the  fuel,  a  heavy  fuel  requiring  heat 
while  a  volatile  fuel  is  easily  vaporized  at  ordinary  temperatures 
by  being  broken  up  in  a  fine  mist.  If  the  fuel  is  in  the  solid 
form,  like  coal,  it  must  be  converted  into  a  gas  by  use  the  of  a 
gas  producer,  to  be  described  later,  before  it  can  be  used  in  the 
gas  engine  cylinder. 

After  the  mixture  is  drawn  into  the  cylinder,  it  is  prepared  for 
ignition  by  compressing  and  intimately  mixing  the  fuel  with  the 
air  at  one  end  of  the  engine  cylinder.  Ignition  of  the  highly 
compressed  explosive  mixture  is  followed  by  a  great  rise  in 
pressure  which  is  utilized  in  producing  work. 

The  Gas-engine  Cycle. — The  series  of  events  which  are 
essential  for  carrying  out  the  transformation  of  heat  into  work 
is  called  the  cycle  of  an  engine.  The  gas-engine  cycle  mostly 
used,  the  Otto  cycle,  comprises  five  events  which  are: 

1.  The  mixture  of  fuel  and  air  must  be  drawn  into  the  engine 
cylinder. 

93 


94  FARM  MOTORS 

2.  The  mixture  must  be  compressed. 

3.  The  mixture  must  be  ignited. 

4.  The  ignited  mixture  expands  doing  work. 

5.  The  cyhnder  must  be  cleaned  of  burned  gases  in  order  to 
receive  a  fresh  mixture. 

The  above  five  events  in  the  order  explained  are  usually  called : 
suction,  compression,  ignition,  expansion,  and  exhaust. 

There  is  another  commercial  gas-engine  cycle,  the  Diesel, 
which  is  used  in  certain  types  of  oil  engines.  The  Diesel  cycle 
also  requires  five  events,  and  differs  from  the  Otto  cycle  in  that 
air  without  fuel  is  compressed  in  the  engine  cylinder  to  such  a 
great  pressure  that  the  temperature  resulting  is  sufficiently 
high  to  ignite  the  fuel  automatically,  as  it  is  sprayed  by  an 
auxiliary  pump  into  the  engine  cylinder. 

The  compression  pressures  carried  in  engines  working  on  the 
Diesel  cycle  are  500  to  700  lb.  per  square  inch,  while  those 
carried  in  engines  working  on  the  Otto  cycle  and  with  the  same 
fuels  are  55  to  80  lb.  per  square  inch. 

Classification  of  Gas  Engines. — Gas  engines  are  divided  into 
two  classes,  according  to  the  number  of  piston  strokes  required 
to  carry  out  the  five  events  of  the  gas-engine  cycle.  To  one  class 
belong  all  engines  which  require  four  complete  strokes  of  the 
piston,  or  two  complete  revolutions  of  the  crank-shaft  to  carry 
out  the  five  events  of  the  gas-engine  cycle.  These  engines  are 
called  four-stroke  cycle  engines.  The  two-stroke  cycle-engine 
works  on  the  same  gas-engine  cycle  as  the  four-stroke  cycle 
engine,  only  the  mechanism  is  modified  so  as  to  carry  out  the  five 
events  in  only  two  strokes  of  the  piston. 


Spark  P/(/cf 


The  Four-stroke  Cycle. — The  action  of  an  internal  combustion 
engine  working  on  the  four-stroke  Otto  cycle  is  illustrated  in 
Figs.  98  to  102. 

1.  Suction  of  the  mixture  of  air  and  gas  through  the  inlet 


GAS  AND  OIL  ENGINES 


95 


valve  takes  place  during  the  complete  outward  stroke  of  the 
piston,  the  exhaust  valve  being  closed.  This  is  shown  in  Tig: 
98. 

2.  On  the  return  stroke  of  the  piston,  shown  in  Fig.  99,  both 
the  inlet  and  exhaust  valves  remain  closed  and  the  mixture  is 


Fig.  99. 


compressed  between  the  piston  and  the  closed  end  of  the  cylinder. 
Just  before  this  stroke  of  the  piston  is  completed  the  compressed 
mixture  is  ignited  by  a  spark  as  illustrated  in  Fig.  100,  and 
rapid  combustion,  or  explosion  takes  place. 


Spark  Pluof 


Exhaust  Valve- 


Fig.  100. 

3.  The  increased  pressure  due  to  the  rapid  combustion  of 
the  mixture  drives  the  piston  on  its  second  forward  stroke, 
which  is  the  power  stroke.     This  is  shown  in  Fig.  101.     Both 


Inlet  Valve 


Exhaust  Valve- 


Fig.  101. 


valves  remain  closed  until  the  end  of  the  power  stroke,  when  the 
exhaust  valve  opens  and  communicates  the  cylinder  with  the 
atmosphere. 

4.  The  exhaust  valve  remains  open  during  the  fourth  stroke 


96 


FARM  MOTORS 


called  the  exhaust  stroke,  Fig.  102,  and  the  burned  gases  are 
driven  out  from  the  cylinder  by  the  return  of  the  piston. 

An  indicator  diagram,  taken  from  a  four-stroke  cycle  engine, 
using  gasoline  as  fuel,  is  illustrated  in  Fig.  103.  IB  is  the  suction 
stroke,  BC  the  compression  stroke,  CD  shows  the  ignition  event, 
DE  is  the  power  stroke  and  EI  is  the  exhaust  stroke.     The 


Inlet  \/'alve 


Spark  Plucf 


^ 


..i^^^^^^^ 


£^/.a.-.//^/;^^°|py..........^ 


'^^^ff^fff/t't'/^n 


W//U^^Y<\ 


Fig.  102. 

direction  of  motion  of  the  piston  during  each  stroke  is  illustrated 
in  each  case  by  arrows.  Lines  AF  and  AG  were  added  to  the 
indicator  diagram,  the  first  is  the  atmospheric  line  while  AG  is 
the  line  of  pressures.  From  Fig.  103  it  will  be  noticed  that  part 
of  the  suction  stroke  occurs  at  a  pressure  lower  than  atmos- 
pheric.    The  reason  for  this  is  that  a  slight  vacuum  is  created 


Suction  Stroke  ■ 

Fig.  103. 


in  the  cylinder  by  the  piston  moving  away  from  the  cylinder 
head.  This  vacuum  helps  to  draw  or  suck  the  mixture  into  the 
cylinder. 

The  engine  working  on  the  four-stroke  cycle  requires  two  com- 
plete revolutions  of  the  crank  shaft,  or  four  strokes  of  the  piston 
to  produce  one  working  stroke.     The  other  three  are  not  only 


GAS  AND  OIL  ENGINES 


97 


idle  strokes,  but  power  is  required  to  move  the  piston  through 
these  strokes,  and  this  has  to  be  furnished  by  storing  extra  mo- 
mentum in  heavy  flywheels.  Several  attempts  were  made  from 
time  to  time  to  produce  an  internal  combustion  engine  by 
modifying  the  Otto  or  Diesel  gas-engine  cycles,  so  that  the 
working  stroke  would  occur  more  frequently.     This  has  resulted 


Fig.  104. 


in  the  so-called  two-stroke  cycle  engine,  to  be  explained  in  the 
next  section,  which  completes  the  cycle  in  two  strokes  requiring 
only  one  complete  revolution  of  the  crank. 

The  Two-stroke  Cycle. — The  two-stroke  cycle  engine  carries 
out^the  gas-engine  cycle  in  two  strokes  by  precompressing  the 
mixture  of  fuel  and  air  in  a  separate  chamber,  and  by  having 


98  FARM  MOTORS 

the  events  of  expansion,  exhaust  and  admission  occur  during  the 
same  stroke  of  the  piston.  The  precompression  of  the  mixture 
is  accompHshed  in  some  engines  by  having  a  tightly  closed  crank 
case,  and  in  other  types  by  closing  the  crank  end  of  the  cylinder, 
and  providing  a  stuffing  box  for  the  piston  rod.  Large  two- 
stroke  cycle  engines  are  usually  made  double  acting  and  an 
additional  cylinder  is  provided  for  the  precompression  of  the 
mixture. 

The  principle  of  the  two-stroke  cycle  internal  combustion 
engine  is  illustrated  in  Fig.  104.  On  the  upward  stroke  of  the 
piston  P,  a  partial  vacuum  is  created  in  the  crank  case  C,  and 
the  explosive  mixture  of  fuel  and  air  is  drawn  in  through  a  valve 
at  A.  At  the  same  time  a  mixture  previously  taken  into  the 
upper  part  of  the  cylinder  W  is  compressed.  Near  the  end  of 
this  compression  stroke,  the  mixture  is  fired  from  a  spark  pro- 
duced by  the  spark  plug  S.  This  produces  an  increase  in  pres- 
sure which  drives  the  piston  on  its  downward  or  working  stroke. 
The  piston  descending  compresses  the  mixture  in  the  crank 
case  to  several  pounds  above  atmospheric,  the  admission  valve 
at  A  being  closed  as  soon  as  the  pressure  in  the  crank  case  ex- 
ceeds atmospheric.  When  the  piston  is  very  near  the  end  of  its 
downward  stroke,  it  uncovers  the  exhaust  port  at  E  and  allows 
the  burned  gases  to  escape  into  the  atmosphere.  The  piston 
continuing  on  its  downward  stroke  next  uncovers  the  port  at  I, 
allowing  the  slightly  compressed  mixture  in*  the  crank  case  C  to 
rush  into  the  working  part  of  the  cylinder  W. 

The  distinctive  feature  of  the  two-stroke  cycle  engine  is  the 
absence  of  valves.  The  transfer  port  I  from  the  crank  case  C 
to  the  working  part  of  the  cylinder  W,  as  well  as  the  exhaust 
port  E,  are  opened  and  closed  by  the  piston. 

Comparison  of  Two-stroke  Cycle  and  Four-stroke  Cycle 
Engines. — To  offset  the  advantages  resulting  from  fewer  valves 
and  greater  frequency  of  working  strokes,  the  two-stroke  cycle 
engine  is  usually  less  economical  in  fuel  consumption  and  not  as 
reliable  as  the  four-stroke  cycle  engine.  As  the  inlet  port^  I  is 
opened  while  the  exhaust  of  the  gases  takes  place  at  E,  there  is 
always  some  chance  that  part  of  the  fresh  mixture  will  pass  out 
through  the  exhaust  port.  Closing  the  exhaust  port  too  soon 
will  cause  a  decrease  in  power  and  efficiency,  on  account  of  the 


GAS  AND  OIL  ENGINES 


99 


mixing  of  the  inert  burned  gases  with  the  fresh  mixture.  By 
carefully  proportioning  the  size  and  location  of  the  ports,  and 
by  providing  the  piston  with  a  lip  L  (Fig.  104)  to  direct  the 
incoming  mixture  toward  the  cylinder  head,  the  above  losses 
may  be  decreased.  In  any  case  the  scavenging  of  the  cylinder 
cannot  be  as  complete  in  the  two-stroke  cycle  as  in  the  four- 
stroke  cycle  engine,  where  one  full  stroke  of  the  piston  is  allowed 
for  the  removal  of  the  exhaust  gases. 

The  two-stroke  cycle  engine  can  be  made  to  run  in  either 
direction  by  a  simple  modification  of  the  ignition  timing  mechan- 


FiG.  105. 


ism.  This  feature,  and  because  of  its  light  weight,  makes  the 
two-stroke  cycle  engine  especially  adaptable  for  the  propulsion 
of  small  boats.  For  stationary  purposes,  in  small  and  medium 
sizes,  and  for  the  propulsion  of  traction  engines,  automobiles 
and  other  vehicles,  the  four-stroke  cycle  engine  is  usually  to  be 
preferred  on  account  of  its  reliability  and  somewhat  better  fuel 
economy. 

Gas-engine  Fuels. — Fuels  for  internal  combustion  engines 
may  be  classified  as  solid,  liquid  and  gaseous.  The  value  of  a 
fuel  for  gas-engine  use  depends  on  the  amount  of  heat  liberated 
when  the  fuel  is  burned,  on  the  cost  of  the  fuel,  and  on  the  cost 
of  preparing  the  fuel  for  use  in  the  gas-engine  cylinder. 


100  FARM  MOTORS 

As  was  explained  in  the  earlier  part  of  this  chapter,  the  fuel 
entering  the  gas-engine  cylinder  must  be  in  the  form  of  a  vapor 
or  a  gas.  For  this  reason  where  a  gaseous  fuel  can  be  obtained 
at  low  cost,  the  complications  of  the  engine  mechanism  are 
reduced.  In  or  near  the  natural  gas  regions,  no  other  gas-engine 
fuel -is  a  competitor  of  the  natural  gas.  Also  in  connection 
with  certain  industrial  processes,  notably  in  the  production  of 
pig  iron,  certain  gaseous  fuels  are  obtained  as  a  byproduct  and 
are  utilized  with  good  results  in  gas  engines.  Illuminating  gas 
is  usually  too  expensive  as  a  gas-engine  fuel. 

Where  coal  is  cheap  and  petroleum  oils  are  expensive  an 
artificial  gas,  called  producer  gas,  has  been  successful,  and  this 
type  of  gas  is  being  used  in  large  as  well  as  comparatively  small 
plants.  An  apparatus  for  making  producer  gas,  called  a  gas 
producer,  is  illustrated  in  Fig.  105.  A  is  a  shell  filled  with  coal 
or  coke,  and  supplied  with  air  and  steam.  Due  to  the  thickness 
of  the  fuel  bed  the  combustion  of  the  fuel  is^  incomplete  and  a 
combustible  gas  is  formed.  The  steam  supplied  enriches  the  gas 
and  prevents  the  formation  of  clinker  by  keeping  down  the 
temperature  of  the  fuel  bed.  S  is  a  scrubber  used  for  cleaning 
the  gas  before  it  is  admitted  to  the  engine  cylinder  C.  B  is  a 
blower  which  is  used  to  furnish  draft  during  the  starting  of  the 
fire  in  the  producer. 

As  a  portable  engine  for  small  powers,  the  internal  combustion 
engine  using  some  liquid  fuel  has  the  greatest  field  of  applica- 
tion. Such  engines  are  especially  suitable  for  intermittent  work 
and  are  ideal  for  farm  use. 

The  liquid  fuels  used  in  internal  combustion  engines  are  gaso- 
line, kerosene,  crude  petroleum,  fuel  oil  and  alcohol. 

Gasoline  and  Other  Distillates  of  Crude  Petroleum. — Gaso- 
line and  kerosene  are  among  the  lighter  distillates  of  crude  petro- 
leum. The  so-called  distillates  are  obtained  by  boiling  or 
refining  crude  petroleum,  and  condensing  the  vapors  which  are 
driven  off  at  various  temperatures. 

The  vapors  which  are  condensed  into  gasoline  are  driven  off 
at  temperatures  of  140  to  160°  F.  The  various  grades  of  kerosene 
are  the  condensed  vapors,  -driven  off  at  temperatures  of  250  to 
400°,  and  the  heavy  oils  are  driven  off  at  still  higher  temperatures. 

Of  all  petroleum  distillates,  gasoline  is  the  most  important 


GAS  AND  OIL  ENGINES  101 

fuel  for  small  internal  combustion  engines.  The  yield  of  gaso-^ 
line,  however,  is  very  small  in  comparison  with  the  heavier  dis- 
tillates. By  refining  American  petroleum,  an  average  of  less  than 
5  per  cent,  of  gasoline  is  obtained  and  usually  about  50  per  cent, 
of  kerosene.  This  makes  gasoline  more  expensive  than  other 
petroleum  fuels.  However,  as  a  fuel  for  small  and  portable 
engines  it  has  the  advantages  of  quick  starting  and  greater 
reliability,  which  more  than  make  up  for  the  greater  cost.  Proc- 
esses are  now  being  perfected  for  extracting  gasoline  from 
natural  gas,  and  there  is  little  doubt  but  what  gasoline  will 
remain  for  many  years  to  come  the  most  important  fuel  for  small 
internal  combustion  engines. 

Gasoline  has  a  flash  point  of  10  to  20°  F.  This  means  that  it 
forms  an  inflamable  Vapor  at  that  low  temperature,  provided  a 
sufficient  supply  of  air  is  present.  For  this  reason  care  must  be 
taken  in  the  handling  of  gasoline.  A  good  storage  tank  free 
from  leaks  and  placed  underground  contributes  greatly  to  the 
safety,  as  well  as  to  the  economical  use  of  gasoline.  When  filling 
a  gasoline  storage  tank  or  in  handling  gasoline,  care  must  be 
taken  not  to  have  any  unprotected  flame  nearby.  In  case 
gasoline  takes  fire  at  the  engine  or  at  the  storage  tank,  it  is  best 
to  extinguish  it  by  means  of  wet  sawdust.  Sand  or  dirt  will 
do  in  an  emergency,  but  if  it  finds  its  way  into  the  engine  cylinder, 
it  may  cause  considerable  damage  by  cutting  the  rubbing 
surfaces. 

The  flash  point  of  kerosene  is  70  to  150°  F.,  depending  on  the 
grade.  As  the  flash  point  of  oil  is  a  measure  of  its  safety,  a  kero- 
sene of  a  lower  flash  point  than  120°  F.  is  dangerous  for  use  as  an 
illuminating  oil  in  lamps.  The  lower  the  flash  point  of  an  oil 
the  better  it  is  for  gas  engine  use,  as  less  heat  is  required  to 
vaporize  it  ready  for  use  in  the  engine  cylinder. 

Very  light  gasoline  has  a  specific  gravity  of  from  0.65  to  0.74. 
The  specific  gravity  of  kerosene  is  0.78  to  0.86,  of  crude  oil  0.87 
to  0.90  and  of  fuel  oil  0.90  to  0.94.  The  specific  gravity  of  petro- 
leum fuels  is  usually  given  in  degrees  of  the  Baume  hydrometer. 
The  relations  existing  between  the  specific  gravity  of  various 
liquid  fuels,  the  degrees  on  the  Baume  hydrometer,  and  the 
weight  of  a  fuel  in  pounds  per  gallon  are  given  in  Table  5. 

A  study  of  Table  5  shows  that  the  weight  per  gallon  of  the 


102 


FARM  MOTORS 


TABLE  5.— RELATION    BETWEEN    SPECIFIC     GRAVITY,    THE 
BAUME  HYDROMETER  SCALE,  AND  THE  WEIGHT  PER  GALLON 


SpeciiSc 

Degrees 

Pounds  per 

Specific 

Degrees 

Pounds  per 

gravity 

Baume 

gallon 

gravity 

Baume 

gallon 

1.000 

10 

8.336 

0.775 

51 

6.462 

Q.993 

11 

8.277 

0.771 

52 

6.428 

0.986 

12 

8.220 

0.767 

53 

6.394 

0.979 

13 

8.161 

0.763 

54 

6.358 

0.972 

14 

8.104 

0.759 

55 

6.324 

0.966 

15 

8.051 

0.755 

56 

6.290 

0.959 

16 

7.997 

0.751 

57 

6.258 

0.953 

17 

7.944 

0.747 

58 

6.212 

0.947 

18 

7.891 

0.743 

59 

6.195 

0.940 

19 

7.837 

0.739 

60 

6.163 

0.934 

20 

7.785 

0.736 

61 

6.133 

0.928 

21 

7.736 

0.732 

62 

6.101 

0.922 

22 

7.687 

0.728 

63 

6.070 

0.916 

23 

7.638 

0.724 

64 

6.038 

0.911 

24 

7.590 

0.721 

65 

6,006 

0.905 

25 

7.541 

0.717 

66 

5.975 

0.899 

26 

7.493 

0.713 

67 

5.946 

0.893 

27 

7.444 

0.710 

68 

5.916 

0.887 

28 

7.395 

0.706 

69 

5.886 

0.881 

29 

7.347 

0.703 

70 

5.856 

0.876 

30 

7.298 

0.699 

71 

5.827 

0.870 

31 

7.254 

0.696 

72 

5.797 

0.865 

32 

7.210 

0.692 

73 

5.771 

0.860 

33 

7.166 

0.689 

74 

5.743 

0.854 

34 

7.122 

0.686 

.  75 

5.715 

0.849 

35 

7.079 

0.682 

76 

5.688 

0.844 

36 

7.038 

0.679 

77 

5.659 

0.840 

37 

6.998 

0.676 

78 

5.632 

0.835 

38 

6.696 

0.672 

79 

5.603 

0.830 

39 

6.918 

0.669 

80 

5.576 

0.825 

40 

.    6.878 

0.666 

81 

5.548 

0.820 

41 

6.839 

0.662 

82 

5.517 

0.816 

42 

6.804 

0.658 

83 

5.487 

0.811 

43 

6.760 

0.655 

84 

5.457 

0.806 

44 

6.721 

0.651 

85 

5.427 

0.802 

45 

6.683 

0.648 

86 

5.402 

0.797 

46 

6.644 

0.645 

87 

5.374 

0.793 

47 

6.608 

0.642 

88 

5.353 

0.788 

48 

6.571 

0.639 

89 

5.316 

0.784 

49 

6.534 

0.639 

90 

5.304 

0.779 

50 

6.498 

GAS  AND  OIL  ENGINES  103 

heavier  oil  is  greater  than  that  of  the  lighter  oils.  Since  the 
calorific  value  per  pound  of  the  various  petroleum  fuels  is  very 
nearly  the  same  (see  Table  4,  Chapter  III),  and  liquid  fuels  are 
bought  by  the  gallon,  it  is  evident  that  the  total  heat  in  a  gallon 
of  kerosene  or  in  that  of  the  still  heavier  oil,  is  much  greater  than 
the  heat  in  a  gallon  of  gasoline.  Kerosene  for  farm  use  has  the 
further  advantages  over  gasoline  in  that  it  can  be  obtained  every- 
where, is  cheaper,  can  be  used  for  illumination  in  lamps  and  is 
not  so  dangerous. 

Any  good  gasoline  engine  can  be  easily  changed  into  one  suit- 
able for  kerosene  fuel.  Such  engines  are  started  on  gasoline  and 
changed  over  to  kerosene  as  soon  as  the  cylinder  walls  become 
hot.  Several  types  of  engines,  to  be  described  later,  will  start 
on  kerosene  and  will  also  operate  on  crude  petroleum  and  on 
fuel  oil.  The  first  cost  of  such  engines  is  greater  than  that  of  a 
gasoline  engine,  and  these  are  used  mainly  in  sizes  of  25  h.p. 
and  larger  for  the  driving  of  pumps  in  irrigation  plants,  and 
also  in  connection  with  electric  light  plants  for  towns  or  cities. 

The  various  type^s  of  gas  tractors,  to  be  described  in  another 
chapter,  are  usually  started  on  gasoline  and  operate  with  kero- 
sene or  with  solar  oil,  which  is  a  heavier  distillate  than  kerosene. 

In  general,  an  engine  running  on  petroleum  fuel  other  than 
gasoline  is  more  difficult  to  start  and  requires  greater  care  and 
more  frequent  cleaning  of  valves  and  pistons.  For  small  engines 
gasoline  has  sufficient  advantages  to  give  it  the  preference  to  the 
cheaper  petroleum  fuels. 

Alcohol  as  a  Fuel  for  Gas-engine  Use. — Alcohol  as  a  fuel  for 
gas-engine  use  has  many  advantages  as  compared  with  the 
petroleum  distillates.  It  is  less  dangerous  than  gasoline,  its 
products  of  combustion  are  odorless,  and  it  lends  itself  to  greater 
compression  pressures  than  do  the  various  petroleum  fuels. 
Recent  experiments  by  the  United  States  Geological  Survey  and 
by  others,  show  that  the  power  of  an  ordinary  gasoline  engine 
can  be  increased  by  about  10  per  cent,  when  using  alcohol.  Also 
that  an  engine  designed  to  stand  the  compression  pressures 
before  ignition  most  suitable  for  alcohol  will  develop  about  30 
per  cent,  more  power  than  a  gasoline  engine  of  the  same  size, 
stroke  and  speed. 

Several  years  ago,  when  the  internal  revenue  tax  was  removed 


104  FARM  MOTORS 

from  alcohol,  so  denatured  as  to  destroy  its  character  as  a  bever- 
age, it  was  expected  that  denatured  alcohol  would  become  a  very 
important  fuel  for  use  in  gas  engines.  Its  price  up  to  this  date, 
however,  has  been  so  much  higher  than  that  of  gasoline,  the  most 
expensive  of  petroleum  fuels,  that  its  use  in  gas  engines  is  out  of 
the  question.  It  is  possible  that,  as  the  cost  of  the  petroleum 
distillates  increases,  and  processes  are  developed  for  producing 
denatured  alcohol  at  a  low  price,  the  alcohol  engine  will  come 
into  prominence  as  a  motor  for  farm  use. 

American  denatured  alcohol  consists  of  100  volumes  of  ethyl 
(grain)  alcohol,  mixed  with  ten  volumes  of  methyl  (wood)  alcohol 
and  with  one-half  a  volume  of  benzol. 

The  specific  gravity  of  denatured  alcohol  is  about  0.795  and 
its  calorific  value  is  about  two-thirds  that  of  petroleum  fuels. 
Alcohol  requires  less  air  for  combustion  than  do  petroleum  fuels. 
Theoretically,  the  calorific  value  of  a  cubic  foot  of  explosive 
mixtures  of  alcohol  and  of  gasoline  is  about  the  same.  Actual 
tests  show  that  the  fuel  economy  per  horse-power  is  about  the 
same  for  both  fuels  provided  the  compression  pressures  before 
ignition  are  best  suited  for  the  particular  fuel  used.  In  gasoline 
engines  compression  pressure  of  75  lb.  are  used,  while  the 
alcohol  engine  gives  best  results,  as  far  as  economy  and  capacity 
are  concerned,  when  the  compression  pressure  before  ignition  is 
180  lb.  per  square  inch. 

Essential  Parts  of  a  Gas  Engine. — The  essential  parts  of  a  gas 
engine  are  illustrated  in  Fig.  106.  I  and  E  are  the  valves  which 
admit  the  mixture  to  and  exhaust  the  mixture  from  the  engine 
cylinder  C.  The  reciprocating  motion  given  to  the  piston  B  is 
communicated  to  the  connecting  rod  D  and  is  changed  into 
rotary  motion  at  the  shaft  F.  The  shaft  F,  while  driving  the 
machinery  to  which  it  is  connected,  also  turns  the  valve  gear 
shaft,  sometimes  called  the  two-to-one  shaft,  through  the  gears 
G  and  H.  The  gear  H  turns  once  for  every  two  revolutions  of 
the  crank,  and  gives  motion  to  the  exhaust  valve  E  through  the 
rod  L  pivoted  at  R.  In  larger  engines  this  valve  gear  shaft  also 
opens  and  closes  the  admission  valve  and  operates  the  fuel  pump 
and  ignition  system.  The  spark  for  igniting  the  mixture  is 
shown  at  O.  As  the  temperatures  resulting  from  the  ignition 
of  the  explosion  mixture  is  usually  over  2000°  F.,  some  method 


GAS  AND  OIL  ENGINES  105 

of  cooling  the  walls  of  the  cylinder  must  be  used  in  orderjto 
facilitate  lubrication,  to  prevent  the  moving  parts  from  being 
twisted  out  of  shape  and  to  avoid  the  ignition  of  the  explosive 
mixture  at  the  wrong  time  of  the  cycle.  One  method  of  cooling 
gas-engine  cylinders  is  to  jacket  the  cylinder  and  allow  water  to 
pass  through  the  jacket  space.  In  the  engine  illustrated  in  Fig. 
106,  the  casting  of  the  jacket  is  extended,  so  that  it  forms  a  box- 
shaped  hopper  M  with  a  large  opening  at  the  top.  The  base  U 
supports  the  various  parts  of  the  engine  and  the  flywheel  W 
carries  the  engine  through  the  idle  strokes.  Besides  the  above 
details,  every  gas  engine  is  usually  provided  with  lubricators 
for  the  cylinder  and  bearings  and  with  a  governor  for  keeping 
the  speed  constant  at  variable  loads. 


Fig.  106. 

The  engine  shown  in  Fig.  106  uses  gasoline  as  fuel,  and  is 
provided  with  a  fuel  tank  S.  A  strainer  V  is  placed  at  the  end 
of  the  pipe  P  to  protect  the  engine  cylinder  from  any  impurities 
which  may  be  contained  in  the  gasoline  tank. 

The  various  parts  of  vertical  and  horizontal  gasoline  engines 
are  illustrated  and  named  in  Figs.  107  and  108. 

Carbureters  for  Gasoline  Engines. — The  function  of  a  car- 
bureter is  to  vaporize  the  gasoline,  mix  it  with  the  correct  pro- 
portion of  air  to  form  an  explosive  mixture,  and  then  deliver  the 
mixture  to  the  engine  cylinder.  A  mixture  of  fuel  and  air  in  the 
proper  proportions  is  one  of  the  most  important  factors  essential 


106 


FARM  MOTORS 


to  the  economical  and  safe  operation  of  a  gasoline  engine.  If 
the  mixture  has  too  little  fuel,  or  is  too  lean,  it  will  be  slow 
burning.  In  fact  it  may  still  be  burning  when  the  inlet  valve 
opens  on  the  suction  stroke  and  the  flame  flashing  back  through 
the  inlet  valve  into  the  carbureter  will  produce  what  is  called 


back-firing,  and  this  may  result  in  considerable  damage  to  the 
engine.  If  the  mixture  is  too  rich,  incomplete  combustion  will 
be  produced  with  the  consequent  loss  of  power. 

In  some  forms  of  carbureters  the  air   is  passed   over   the 


GAS  AND  OIL  ENGINES 


107 


surface  of  the  gasoline  on  its  way  to  the  engine  and  becomes 
saturated  with  the  fuel.  In  another  type,  called  the  bubbling' 
carbureter,  the  air  is  made  to  bubble  through  the  fuel.     The  ob- 


EXHAU3T  VALVE  SPRING  WA5HEI 


EXHAU5T  VAIVE  LEVER 
VALVE  ROD  HEAD 


I6NIT0R  TRIP  ROLLER 
IQNITOR  TRIP  CLAMP 


SIGHT  FEED  LUBRICATOR 


Fig.  108. 


jection  to  these  types  of  carbureters  is  that  the  air  combines 
with  only  the  more  volatile  portion  of  the  fuel,  leaving  the 
heavier  constituents  not  vaporized. 


108 


FARM  MOTORS 


In  the  best  forms  of  carbureters  the  gasoline  is  sprayed  into 
the  stream  of  air;  this  method  utilizes  the  heavier  portions  as 
well  as  the  more  volatile  vapors  of  the  fuel. 

In  all  spray  carbureters  the  gasoline  is  delivered  to  a  nozzle 
at  constant  pressure.  In  one  type  of  carbureter,  often  called 
a  mixer  valve,  this  constant  pressure  is  obtained  by  a  pump 
keeping  the  height  of  the  fuel  at  a  uniform  level  in  a  small 
reservoir.  The  level  of  the  fuel  in  the  reservoir  is  maintained 
by  an  overflow  pipe.  This  type  of  carbureter  is  well  suited  for 
stationary  and  semi-portable  engines,  and  it  is  also  used  in  some 
gasoline  traction  engines. 

For  automobiles,  boats,  portable  engines  and  traction  engines 
the  float-feed  type  of  carbureter  is  usually  used.  In  the  case 
of  this  carbureter  the  gasoline  is  admitted  to  a  float  chamber  by 

gravity  from  a  tank  placed  above  the 
engine  cylinder,  the  amount  of  fuel  en- 
tering the  chamber  being  regulated  by 
a  copper  or  cork  float  operating  the 
gasoline  valve.  Most  carbureters  of 
the  float-feed  type  are  automatic  in 
their  action,  in  that  the  quality  of  the 
mixture  is  adjusted  to  suit  the  speed  at 
which  the  motor  is  running. 

One  form  of  mixer  valve,  or  pump- 
feed  carbureter,  is  illustrated  in  Fig. 
109.  A  pump  operated  by  the  valve 
gear  shaft  of  the  engine  forces  the  gaso- 
[line  through  the  supply  pipe  A  to  the 
reservoir  B.  0  is  the  overflow  or  return  pipe  which  maintains 
the  fuel  at  a  constant  level  in  the  reservoir,  and  slightly  below 
the  point  at  which  the  needle  valve  V  enters  the  gasoline  nozzle 
N.  When  the  piston  of  the  engine  starts  on  the  suction  stroke, 
a  partial  vacuum  is  created  in  the  cylinder;  the  inlet  valve  is 
opened  and  a  current  of  air  is  forced  by  the  atmospheric  pressure 
into  the  cylinder.  This  current  of  air  enters  through  the  air 
pipe  C,  attains  a  high  velocity,  and  carries  with  it  into  the 
cylinder  a  portion  of  the  gasoline  vapor.  This  is  the  reason 
why  the  air  passage  of  a  carbureter  is  so  arranged,  that  the 
velocity  of  the  air  is  increased  as  it  passes  around  the  gaso- 


FiG.  109. 


GAS  AND  OIL  ENGINES  109 

line  spray  nozzle.  The  greater  the  velocity  of  the  air  at  the 
nozzle  the  more  vapor  is  carried  into  the  engine  cylinder. 
When  starting  an  engine  by  hand  with  this  form  of  carbureter, 
a  damper  or  throttle  in  the  air  pipe  is  closed,  so  that  the  veloc- 
ity of  the  air  is  increased  sufficiently  to  admit  the  fuel  to  the 
cyhnder.  The  relative  positions  of  the  air  throttle  and  mixer 
are  illustrated  in  Fig.  110. 

Another  form  of  mixer  valve  is  illustrated  in  Fig.  111.  Air 
enters  at  the  lower  opening  C,  gasoline  flows  in  at  5  and  the  mix- 
ture of  air  and  fuel  leaves  the  mixer  valve  at  B.  The  amount  of 
gasoline  fed  is  regulated  by  adjusting  the  needle  valve  at  P. 


EXHAUST  PORT 


CASOLINf 
fEtOCUP 


Fig.  110. 

When  the  engine  piston  moves  on  its  outward  stroke  the  disc  F 
is  raised  by  suction,  drawing  in  a  charge  of  air  through  the  seat 
opening  and  past  the  gasoline  port  into  the  mixing  chamber 
above  F.  The  lift  and  movement  of  the  valve  F,  and  conse- 
quently the  quantity  of  the  mixture  to  the  cylinder,  is  regulated 
by  the  stem  6.  The  gasoline  is  supplied  to  the  carbureter  from 
a  constant  head  reservoir  in  a  manner  similar  to  that  described 
in  connection  with  Fig.  109. 

Automatic  or  float-feed  carbureters  are  provided  with  two 
chambers,  one  a  float  chamber  in  which  a  constant  level  of  the 
fuel  is  maintained  by  means  of  a  float,  the  other   a   mixing 


no 


FARM  MOTORS 


chamber  through  which  the  air  passes  and  mixes  with  the  fuel. 
The  float  and  mixing  chambers  may  be  placed  side  by  side,  or 
the  two  chambers  may  be  constructed  concentric. 

A  float-feed  carbureter  with  the  two  chambers  side  by  side  is 
illustrated  in  Fig.  112.  In  the  float  chamber  is  placed  a  float 
made  either  of  cork  or  of  metal.  The  hollow  metal  float  is  more 
expensive  and  is  liable  to  leak.  Cork  floats  when  covered 
thoroughly  with  shellac  will  not  lose  their  buoyancy,  but  there  is 
some  danger  that  particles  may  become  detached  from  the  cork 
and  clog   the  passages  leading  to  the  spray  nozzle.     When  the 


Fig.  111. — Lunkenheimer  mixer  valve. 


Fig.  112. 


float  chamber  becomes  filled  with  gasoline  to  a  certain  level, 
the  float  lifts  a  ball  or  a  needle  valve,  and  the  flow  of  fuel  is 
stopped.  The  fuel  from  the  float  chamber  enters  the  mixing 
chamber  at  the  left,  is  picked  up  by  the  air  coming  at  high 
velocity,  and  the  mixture  passes  to  the  engine  cylinder. 

A  concentric  float-feed  type  of  carbureter  is  illustrated  in  Fig. 
113.  K  represents  the  float,  which  operates  the  float  valve  V  and 
regulates  the  amount  of  gasoline  entering  the  float  chamber  W 
through  fuel  inlet  at  G.  The  air  inlet  to  the  carbureter  is  at 
D.  A  is  the  gasoline  adjusting  screw  which  regulates  the  needle 
valve.  The  passage  of  the  mixing  chamber  around  the  top  of  the 
spraying  nozzle  J  is  constructed  so  as  to  increase  the  velocity  of 
the  air  at  that  point.     This  part  is  called  the  throat  or  Venturi 


GAS  AND  OIL  ENGINES 


111 


tube  of  the  carbureter.  The  amount  of  mixture  which  is  allowed 
to  pass  through  the  gas  outlet  C  to  the  engine  cylinder  is  regu- 
lated by  the  throttle  E.  As  the  throttle  E  is  opened  and  the 
speed  of  the  motor  increases,  the  velocity  of  the  air  at  the  Venturi 
passage  becomes  great  and  too  much  fuel  is  pulled  in  by  the  air. 
To  overcome  this,  the  latest  carbureters  are  arranged  with 
auxiliary  valves  which  are  controlled  by  the  balls  M.  These 
auxiliary  valves  admit  more  air  as  the  speed  of  the  motor  increa  ses 
and  the  mixture  is  diluted  before  it  is  allowed  to  enter  the  engine 
cylinder. 


Fig.  113. 


Most  float-feed  carbureters  are  provided  with  some  hand- 
operated  method  for  priming  the  carbureter.  This  is  accom- 
plished by  depressing  the  float,  so  that  an  excess  of  gasoline  may 
be  allowed  to  enter  the  mixing  chamber. 

Carbureting  Kerosene  and  the  Heavier  Fuels. — The  various 
forms  of  carbureters  described  cannot  be  used  for  kerosene  or  for 
the  heavier  petroleum  fuels,  as  these  fuels  are  less  volatile  than 
gasoline  at  ordinary  temperatures  and  pressures.  The  heavier 
the  fuel  the  more  heat  is  required  to  vaporize  it. 


112  FARM  MOTORS 

An  ordinary  gasoline  engine  will  operate  v/ith  kerosene  fuel, 
if  started  on  gasoline,  but  carbon  deposits  in  the  cylinder  will 
necessitate  frequent  cleaning  of  the  cylinder  walls,  piston  and 
rings. 

Some  engines  work  very  successfully  with  kerosene  and  solar 
oil,  if  the  fuel  is  vaporized  by  the  exhaust  gases  in  a  coil  located 
entirely  outside  of  the  engine  cylinder.  It  has  been  found  that 
the  injection  of  water  with  the  fuel  reduces  the  carbon  deposits  in 
the  cylinder  and  improves  the  operation  of  the  engine. 

Oil  engines  for  burning  fuels  heavier  than  40°  Baume  have  been 
perfected.  These  engines  are  either  of  the  Diesel  or  semi- 
Diesel  types,  and  ignite  the  fuel  automatically.  The  principle  of 
construction  of  engines  for  heavy  fuels  will  be  explained  in  the 
section  on  ''ignition." 

Cooling  of  Gas-engine  Cylinder  Walls. — The  necessity  for 
cooling  gas-engine  cylinder  walls  was  explained  in  an  earlier  part 
of  this  chapter.  In  smaller  engines  only  the  cylinder  or  cylinder 
and  cylinder  head  must  be  cooled.  In  large  engines  it  becomes 
necessary  to  cool  also  the  piston  and  exhaust  valve. 

Three  methods  are  used  for  cooling  gas  engines: 

1.  Air  cooling. 

2.  Water  cooling. 

3.  Oil  cooling. 

An  air-cooled  gasoline  engine  is  illustrated  in  Figs.  114  and  115. 
The  cylinder  is  cast  with  webs,  and  air  is  forced  by  means  of  a 
fan  driven  from  the  engine.  In  very  small  engines  natural  air 
circulation  is  used.  The  air-cooling  system  has  not  been  found 
practical  for  engines  above  5  h.p.  Even  for  small  engines 
there  is  no  positive  temperature  control  with  this  system  of 
cooling.  This  often  results  in  the  decomposition  of  the  cylinder 
oil  and  in  carbon  deposits  on  the  piston  and  cylinder  walls. 

Cooling  of  cylinder  walls  by  means  of  water  is  the  most  com- 
mon method.  In  this  case  the  cylinder  barrel  or  the  cylinder 
barrel  and  cylinder  head  are  jacketed,  that  is  they  are  built 
with  double  walls  and  water  is  circulated  through  the  space 
between  the  walls.  One  method  of  water  cooling  was  illustrated 
in  connection  with  the  hopper-cooled  engine  in  Fig.  106.  In 
this  case  the  water  is  heated  by  contact  with  the  hot  cylinder 
walls,  rises  and  is  replaced  by  cooler  water. 


GAS  AND  OIL  ENGINES 


113 


Another  system  of  water  cooling  is  to  place  a  galvanized^ 
iron  tank  filled  with  water  near  the  e  gine  and  connect  the  lower 
part  of  the  cylinder  jafcket  to  the  bottom  of  the  tank  and  the 
upper  part  of  the  jacket  at  the  top  of  the  tank.  The  cold  water 
enters  the  jacket  at  the  bottom,  is  heated,  rises  and  flows  to  the 
upper  part  of  the  tank,  the  water  circulation  being  similar  to 
that  of  the  hopper-cooled  engine. 


Fig.  114. 


In  order  to  definitely  control  the  temperature  of  the  water 
jacket,  the  forced  system  of  water  circulation  shown  in  Fig.  116 
is  preferable  to  the  two  described.  This  system  is  used  when  a 
constant  source  of  water  supply  is  available.  The  temperature 
in  the  jacket  is  usually  maintained  at  about  150°. 


114 


FARM  MOTORS 


Another  method  of  water  cooling  by  forced  circulation,  used 
quite  extensively  on  small  stationary  and  portable  engines,  is 
illustrated  in  Fig.  117.  The  water  from  the  lower  part  of  the 
tank  T  is  forced  by  a  pump  through  the  jacket.  The  water 
enters  the  bottom  of  the  jacket,  and  leaves  from  the  top  of  the 
jacket  by  the  pipe  P.  The  water  is  then  allowed  to  pass  over 
the  screen  S  and  is  cooled  by  evaporation  before  reentering  the 
tank.     The  advantage  of  this  system  is  that  the  screen  acts  as  a 


Fig.  115. 

cooling  tower  and  reduces  the  weight  of  water  which  must  be 
carried  with  the  engine. 

Oil  is  being  used  for  cooling  gas-engine  cylinders  to  a  limited 
extent  where  the  engines  are  exposed  to  low  temperatures. 
The  systems  of  oil  cooling  are  similar  to  water  cooling.  In 
some  cases  natural  circulation  is  employed,  using  hoppers  or 
tanks,  while  in  other  types  some  form  of  forced  cooling  like  the 
one  illustrated  in  Fig.  117  is  used.  However,  oil  is  not  a  satis- 
factory cooling  medium  on  account  of  its  inability  to  take  up 
heat  as  easily  as  water. 


GAS  AND  OIL  ENGINES 


115 


4f^- 


y  fxhausi  \/alye 


Fig.  116. 


MUFFLER 


Fig.  117. 


116 


FARM  MOTORS 


s 


In  some  cases  non-freezing  mixtures  composed  of  wood  alcohol 
and  glycerine  have  been  used  for  cooling  the  cylinders  of  gas 
engines.  Calcium  chloride  and  common  salt  have  also  been 
used  to  some  extent  for  the  cooling  of  engines.  These  mixtures 
will  tend  to  prevent  freezing  and  the  consequent  cracking  of  the 
jacket  and  cylinder  walls  during  cold  weather  when  the  engine 
is  not  running. 

When  water  is  the  cooling  medium,  the  engine  should  be  pro- 
vided with  a  drain  cock  at  the  lowest  point  of  the  jacket,  so 
that  the  jacket  can  be  thoroughly  drained  in  freezing  weather. 

Gas-engine  Ignition  Systems. — Ignition  in  all  modern  gas 
engines  is  accompHshed  either  by  an  electric  spark,  or  automat- 
ically by  the  high  compression  to  which  either  the  air  or  the  mix- 
ture is  subjected  in  the  engine  cylinder. 

In  some  older  makes  of  engines  the 
X  hot  tube  system  of  ignition  is  still 

p  employed,  in  which  a  tube,  made  of 

porcelain  or  of  some  nickel  alloy,  is 
open  at  one  end  to  the  cylinder  and  is 
closed  at  the  other.  The  closed  end 
of  the  tube  is  heated  by  a  Bunsen 
burner.  A  portion  of  the  explosive 
mixture  is  forced  into  the  tube  dur- 
ing the  compression  stroke  of  the  pis- 
ton, and  is  fired  by  the  heat  of  the 
tube  walls.  Accurate  timing  of  the 
point  of  ignition  is  quite  impossible  with  the  hot  tube  system. 
The  only  points  in  favor  of  this  system  are  the  low  first  cost  and 
cost  of  maintenance  as  compared  with  the  electric  system. 

Electric  Ignition  Systems  for  Gas  Engines. — There  are  two 
systems  of  electric  ignition : 

1.  The  make  and  break. 

2.  The  jump  spark. 

A  student  not  familiar  with  the  fundamentals  of  electricity 
will  do  well  to  study  Chapter  X  before  taking  up  electric  ignition. 

The  principle  of  the  make-and-break  system  is  illustrated  in 
Fig.  118.  B  is  a  battery  which  supplies  the  electric  current  for 
ignition.  C  is  an  inductive  spark  coil,  often  called  a  kick  coil. 
It  consists  of  a  bundle  of  soft  iron  wires  surrounded  by  a    coil 


^o-e©©©©©^ 


Fig. 


B 

118. 


GAS  AND  OIL  ENGINES 


117 


of  insulated  copper  wire  through  which  the  current  passes^  On 
account  of  the  inductive  action  of  such  a  coil,  the  spark  is 
greatly  intensified.  S  is  a  stationary  electrode  well  insulated 
from  the  engine  and  M  is  a  movable  electrode  not  insulated 
from  the  engine.  The  contact  points  of  the  two  electrodes 
are  brought  together  by  means  of  a  cam  T  operated  from  the 
valve  gear  shaft  of  the  engine.  When  the  switch  W  is  closed, 
current  will  flow  through  the  circuit  as  soon  as  the  contact 
points  of  the  electrodes  are  brought  together  by  the  cam  T.     A 


Fig.  119. 


sudden  breaking  of  the  contact,  aided  by  a  spring,  causes  a 
spark  to  pass  between  the  points  which  ignites  the  mixture.  > 
The  contact  between  the  two  electrodes  of  the  make-and- 
break  system  can  be  made  by  sliding  one  contact  point  over  the 
other,  this  being  known  as  the  wipe-spark  igniter  and  is  illus- 
trated in  Fig.  119.  A  is  the  movable  and  B  is  the  stationary 
electrode.  Another  type  shown  in  Fig.  120  is  called  the  hammer 
break  igniter.  S  is  the  stationary  and  M  is  the  movable  elec- 
trode. The  interrupter  lever  I  is  operated  from  a  cam  on  the 
valve  gear  shaft  until  the  two  contact  points  M  and  S  are  brought 


118 


FARM  MOTORS 


in  contact.  At  the  desired  time,  I  is  tripped  and  flies  back, 
instantly  breaking  the  contact  and  producing  an  arc  between 
M  and  S.  Another  form  of  hammer  make  and  break  igniter 
is  illustrated  in  Fig.  121. 


Fig.  120. 

Wipe  spark  igniters  keep  the  contact  points  cleaner  than 
hammer  break  types.  The  hammer  break  igniter  is  more  com- 
monly used  on  account  of  the  easier  adjustment  and  less  wear  of 
the  contact  points. 


Fig.  121. 


The  principle  of  the  jump-spark  system  is  illustrated  in  Fig. 
122.  A  is  a  spark  plug,  the  spark  points  E  and  F  of  which 
project  into  the  cylinder.  These  spark  points  are  stationary, 
insulated  from  each  other,  and  separated  by  an  air  gap  of  about 
1/16  in.  When  the  switch  W  is  closed  the  current  from  the 
battery  B  flows  through  the  timer  T,  which  completes  the  circuit 


GAS  AND  OIL  ENGINES 


119 


at  the  proper  time  through  the  induction  coil  I,  and  the  induced 
current  produces  a  spark  at  the  spark  plug  gap,  igniting  the 
explosive  mixture  in  the  cylinder. 

The  method  of  wiring  batteries,  coil,  timer  and  spark  plug  is 
well  illustrated  in  Fig.  123. 

The  induction  coil  I,  Fig.  122,  differs  from  the  inductance  coil 
used  in  connection  with  the  make-and-break  system  of  ignition, 
in  that  two  layers  of  insulated  wire  are  wound  on  the  core  of  the 
induction  coil  and  only  one  layer  in  the  case  of  the  inductance 
coil.  One  of  the  layers,  called  the  primary,  consists  of  several 
turns  of  fairly  large  insulated  copper  wire.  The  other  winding 
is  a  coil  of  many  turns  of  very  fine  insulated  wire  and  has  no 


Fig.  122. 


metallic  contact  with  the  primary.  In  Fig.  122,  P  represents 
the  primary,  S  the  secondary,  and  C  the  core,  which  consists  of  a 
bundle  of  soft  iron  wire.  The  current  from  the  battery  B  (Fig. 
122)  enters  the  primary  winding  of  the  induction  coil  P  and 
induces  a  high-voltage  current  in  the  secondary  winding  S.  This 
high-voltage  current  is  sufficiently  powerful  to  produce  a  spark 
in  the  air  gap  of  the  spark  plug  A. 

An  induction  coil  is  shown  in  Fig.  124.  This  coil  differs  from 
the  one  described  (Fig.  122)  by  the  addition  of  a  vibrator,  trem- 
bler or  interrupter  R.  The  function  of  this  vibrator  is  to  inter- 
rupt the  primary  circuit  with  great  rapidity;  this  action  induces 
an  alternating  current  in  the  secondary  and  a  series  of  sparks  at 
the  air  gap  of  the  spark  coil. 


120 


FARM  MOTORS 


All  induction  coils  are  also  provided  with  an  electric  con- 
denser, which  consists  of  alternate  layers  of  tin-foil  and  some 


Fig.  123. 


Fig.  124. 


Fig.  125. 


insulating  material  like  paraffined  paper.  The  condenser  acts 
like  an  air  chamber  of  a  pump,  in  that  it  absorbs  the  excess  of 
current  at  the  primary  winding,  prevents  sparking  at  the  vibrator 


GAS  AND  OIL  ENGINES 


121 


and  gives  out  this  excess  at  the  proper  time  to  increase  the  intent. 
sity  of  the  spark. 

An  inductance  coil  suitable  for  the  make-and-break  system  of 
ignition  is  shown  in  Fig.  125. 

A  spark  plug  used  in  connection  with  the  jump-spark  system 
of  ignition  is  illustrated. in  Fig.  126.     It  consists  essentially  of 
two  platinum  wire  points,  well  insulated  from  each  other.     The 
central  point   is   connected  to  the  binding 
post  which  receives  current  from  the  second- 
ary, or  high-tension  winding  of  the  induction 
coil.     The  other  point  is  not  insulated  from 
the  thread,  and  completes  the  circuit  when 
the  spark  plug  is  in  the  engine  cylinder. 

Comparing  the  two  systems  of  electric 
ignition,  the  jump-spark  system  is  much 
more  simple  mechanically  as  it  has  no  mov- 
ing parts  inside  the  cylinder.  The  make- 
and-break  system  is  simpler  electrically, 
does  not  have  to  be  insulated  so  carefully 
and  the  spark  is  more  certain.  The  make- 
and-break  system  is  usually  used  on  station- 
ary engines  and  to  some  extent  on  traction 
engines.  The  jump-spark  system  is  better 
adapted  for  high-speed  engines  than  is  the 
make-and-break,  and  is  used  on  automobiles, 
small  stationary  engines,  marine  engines  and 
also  on  traction  engines. 

In  regard  to  the  sources  of  electricity  for 
ignition,  this  may  be  derived  from  an  ordi- 
nary lighting  circuit,  from  a  primary  cell, 
from  a  storage  battery,  or  from  some  form  of  small  ignition 
dynamo  or  magneto. 

The  primary  and  storage  batteries  are  fully  explained  in 
Chapter  X. 

An  ignition  dynamo  is  a  miniature  direct-current  dynamo, 
built  on  the  same  plan  as  any  large  dynamo  used  for  lighting. 
It  has  electromagnets  as  field  magnets  and  is  usually  of  the  iron- 
clad type.  One  form  of  ignition  dynamo  is  shown  in  Fig.  127. 
In  using  an  ignition  dynamo  the  engine  must  be  started  on 


'■■K-^mm 


Fig.  126. 


122 


FARM  MOTORS 


batteries,   as   the   speed    developed   when   turning  the  engine 
by  hand  is  insufficient  to  produce  a  spark  of   sufficient   in- 


FiG.  127. 


Fig.  128. 


tensity  by  the  dynamo.  As  soon  as  the  engine  speeds  up,  the 
battery  current  is  thrown  off  and  the  spark  is  supplied  by  the 
ignition  dynamo.     Most  ignition  dynamos  will  supply  a  spark  of 


GAS  AND  OIL  ENGINES 


123 


sufficient  intensity  for  a  make-and-break  system  of  ignition^ 
without  an  inductance  coil.  For  jump-spark  ignition  a  special 
induction  coil  must  be  used  with  the  ignition  dynamo. 

The  magneto  differs  from  the  ignition  dynamo  in  that  its  fields 
are  permanent  magnets  instead  of  electromagnets.  For  this 
reason  the  magneto  may  be  run  in  either  direction  and  at  any 
desired  speed.  Magnetos  should  always  be  positively  driven 
from  the  engine,  as  there  must  be  a  definite  relation  between 
the  time  the  spark  is  produced  by  the  magneto  and  the  posi- 
tion of  the  crank  shaft. 


Longitudinal  Section. 


Rear  View. 


1.  Contact  plate 

2.  Slip  ring  with  distributor  segment. 

3.  Carbon. 

4.  Carbon  holder. 

5.  Contact  breaker  disc 

6.  Bell  crank  lever. 

7  Bell  crank  lever  spring 


8.  Contact  piece. 

9.  Fastening  screw  for  contact 
breaker. 

10.  Timing  lever. 

11.  Steel  segment. 

12.  Short-circuiting  screw. 

13.  Flat  spring  for  timing  lever. 


14.  Brass  end  cap. 

15.  Flat  spring. 

16.  Bolt  for  spring  15. 
17    Condenser. 

18.  Dust  cover. 

19.  Short  platinum  screw. 

20.  Long  platinum  screw. 


Fig.  129. 


Magnetos  are  of  two  types: 

1.  The  low-tension  magneto  shown  in  Fig.  128  is  used  instead 
of  a  battery  and  inductance  coil  for  make-and-break  systems  of 
ignition. 

2.  The  high-tension  magneto  (Fig.  129)  is  used  for  jump- 
spark  systems  of  ignition.  It  differs  from  the  low-tension  mag- 
neto, in  that  the  armature  is  provided  with  two  windings,  a  pri- 
mary and  a  secondary,  and  also  includes  a  condenser.     The 


124 


FARM  MOTORS 


high-tension  magneto  takes  the  place  of  the  battery,  induction 
coil  and  condenser  for  the  jump-spark  system. 

Automatic  Ignition  for  Oil  Engines. — One  type  of  oil  engine, 
the  Hornsby  Akroyd,  is  illustrated  in  Fig.  130.  The  engine  is 
provided  with  an  unjacketed  vaporizer  A,  which  communicates 
with  the  cylinder  by  means  of  the  small  opening  B.  This  vapor- 
izer is  raised  to  a  red  heat,  before  starting  by  means  of  a  torch, 
and  is  kept  hot  by  repeated  explosions  when  the  engine  is  running. 
This  engine  works  on  the  regular  four-stroke  Otto  gas  engine 
cycle.     During  the  suction  stroke  of  the  piston  only  air  is  sucked 


into  the  cylinder  and  the  charge  of  oil  fuel  is  injected  into  the 
vaporizer  by  a  pump.  On  the  return  stroke  the  air  is  compressed, 
forced  in  the  vaporizer,  mixed  with  the  fuel  and  automatically 
ignited.  This  is  followed  by  the  expansion  and  exhaust  strokes, 
as  in  other  internal  combustion  engines. 

A  modification  of  this  type  of  engine  is  the  so-called  semi- 
Diesel  type  of  oil  engine,  which  is  well  adapted  for  the  burning 
of  the  lowest  grades  of  petroleum  fuels.  In  this  case  the  air  is 
compressed  to  about  250  lb.  per  square  inch  before  the  fuel  is 
injected  into  the  cylinder. 


GAS  AND  OIL  ENGINES  125 

The  Diesel  engine  was  mentioned  in  the  first  part  of  this  chap- 
ter. It- is  very  economical  for  the  burning  of  low  grades  of  fuel, 
but  the  high  first  cost  of  the  engine  limits  its  field  of  application. 

Governing  of  Gas  Engines. — Every  gas  engine  must  be  pro- 
vided with  some  governin.g  mechanism  in  order  that  its  speed 
may  be  kept  constant  as  the  power  developed  by  the  engine  va- 
ries. The  governing  mechanism  is  operated  by  the  speed  varia- 
tions of  the  engine  and  the  speed  control  is  accomplished  by  the 
following  methods. 

1.  Hit-or-miss  Governing.  In  this  system  the  number  of 
explosions  is  varied  according  to  the  load  on  the  engine.  This 
can  be  carried  out  in  several  ways,  dependin.g  on  the  valve  gear 
of  the  engine. 

In  the  case  of  small  engines,  where  the  inlet  valve  is  auto- 
matically operated  by  the  vacuum  created  in  the  cylinder  during 
the  suction  stroke,  the  governor  operates  on  the  exhaust  valve 
by  holding  it  open  during  the  suction  stroke.  The  free  communi- 
cation of  the  engine  cylinder  with  the  outside  prevents  the  form- 
ation of  sufficient  vacuum  in  the  cylinder  to  lift  the  inlet  valve. 

When  the  inlet  valve  is  mechanically  operated  from  the  valve 
gear  shaft,  the  governor  acts  on  the  inlet  valve  keeping  it  closed 
part  of  the  time  at  light  loads.  The  governor  used  to  accomplish 
this  is  usually  some  form  of  flyball  governor.  As  the  speed  of 
the  engine  increases,  the  balls  are  thrown  out  by  centrifugal  force 
and  shift  the  position  of  a  cam  on  the  valve  gear  shaft  preventing 
the  opening  of  the  inlet  valve. 

The  hit-or-miss  system  of  governing  can  also  be  carried  out  by 
having  the  governor  open  a  switch,  thus  interrupting  the  flow 
of  current  to  the  igniter,  as  the  load  decreases.  This  method  is 
very  wasteful  of  fuel  as  the  fuel  drawn  in  at  each  suction  stroke 
passes  through  the  engine  and  is  wasted.  It  should  be  used 
only  in  connection  with  one  of  the  other  methods  of  governing. 

The  hit-or-miss  system  of  governing  is  very  simple  and  gives 
good  fuel  economy  at  variable  loads.  As  the  explosions  in  the 
engine  do  not  occur  at  regular  intervals,  this  system  of  governing 
necessitates  the  use  of  very  heavy  flywheels  in  order  to  keep  the 
speed  fluctuations  within  practical  limits.  The  hit-or-miss 
system  is  very  well  adapted  for  small  and  also  for  medium  size 
engines  where  very  close  speed  regulation  is  not  essential. 


126 


FARM  MOTORS 


2.  Varying  Quantity  of  Mixture. — In  this  system  the  propor- 
tion of  air  to  fuel  is  kept  constant  and  the  quantity  of  the  mix- 
ture admitted  into  the  cylinder  is  varied  according  to  the  load. 
This  variation  is  accomplished  either  by  throttling  the  charge  or 
by  changing  the  time  during  which  the  inlet  valve  is  open  to  the 
cylinder.  In  fact  the  two  methods  of  varying  the  quantity  of 
the  mixture  are  similar  to  those  used  in  governing  steam  engines 
and  as  explained  in  Chapter  V. 


Fig.  131. 


3.  Varying  Quality  of  Mixture. — In  this  case  the  total  quantity 
admitted  into  the  cylinder  is  kept  constant,  but  the  amount  of 
fuel  mixed  with  the  air  is  varied  according  to  the  load. 

When  gas  engines  are  governed  by  varying  the  quantity  or 
quality  of  the  mixture,  the  speed  is  more  uniform  at  variable 
loads.  Also  since  the  explosions  occur  at  definite  periods,  the 
temperatures  inside  of  the  cylinder,  are  kept  more  constant. 
The  throttling  form  of  governor  is  used  most  commonly  with 
traction  engines. 

The  Gasoline  Engine  on  the  Farm. — Some  of  the  uses  to  which 
a  gasoline  engine  can  be  applied  on  the  farm  are  illustrated  in 
Figs.  131  to  141. 


GAS  AND  OIL  ENGINES 


127 


A  12-h.p.  gasoline  engine  is  shown  driving  an  ensilage  cul 
and  silo  filler  in  Fig.  131. 


Fig.  132. 


Fig.  133. 


Another  engine  of  3  1/2  h.p.  drives  a  corn  sheller,  Fig.  132. 
A  7-h.p.  engine  is  illustrated  in  Fig.  133  driving  a  hay  press. 


128 


FARM  MOTORS 


^ 

1   /^^ 

/ 

mji 

HHir^^  \* 

1 

^     '^i^ffii^^ 

A 

■1 

'^^k 

P 

■-— 

r 

/..-^  .-..,-./,» 

1B,r 

n 

k. 

J 

Fig.  134. 


Fig.  135, 


GAS  AND  OIL  ENGINES  129 

A  binder  driven  by  a  4-h.p.  engine  is  shown  in  Fig.  134.      _ 
An  air-cooled  gasoline  engine  of  2  h.p.,  direct-connected  to  a 
spraying  outfit  (Fig.  135),  is  capable  of  producing  a  pressure  of 
100  lb.  per  square  inch  or  more,  as  compared  with  about  50  lb. 
in  the  case  of  the  hand  sprayer. 


Fig.  136. 

The  application  of  the  gasoline  engine  to  pumping  water  for 
household  use  and  for  irrigation  is  illustrated  in  Figs.  136  and 
137. 

Figures  138,  139  and  140  show  the  application  of  the  small 
gasoline  engine  for  the  driving  of  cream  separators,  churns  and 
washing  machines. 

A  wood-sawing  rig,  Fig.  141,  can  be  removed  by  loosening 


130  FARM  MOTORS 

clamp  bolts,  and  the  engine  used  for  grinding  feed,  pumping, 
shredding  or  for  any  other  farm  work  within  its  capacity. 


Fig.  137. 

Other  uses  to  which  the  gasoline  engine  can  be  put  include : 
the  driving  of  cement  mixers,  and  rock  crushers,  the  grinding  of 


F^ 

^^^^^^Hi/ 

m 

w^ 

IH! 

Fig.  138. 


feed,  the  driving  of  grindstones  and  other  tools  in  the  farm  shop, 
the  driving  of  electric  generators  for  farm  lighting  (see  Chapter 


GAS  AND  OIL  ENGINES 


131 


X),  and  for  various  other  work  about  the  house,  barn  and  dairy^ 
which  require  power. 


'<^ 

ik 

^t 

^m 

^IhI^^^^^H    ^m^fr     ^ 

%- 

! 

Fig.  139. 


Fig.  140. 


Gas  tractors  and  their  field  of  application  will  be  taken  up  in 
Chapter  VII. 


132  FARM  MOTORS 

Selection  and  Management  of  Gas  and  Oil  Engines 

Selecting  a  Gas  Engine. — A  gas  engine  should  be  selected 
large  enough  to  do  the  required  work,  as  it  will  stand  but  little 
overload.  This  is  due  to  the  fact  that  the  gas  engine  develops 
its  maximum  power,  when  a  full  charge  of  the  best  mixture  of 
fuel  and  air,  at  the  maximum  density,  has  been  admitted  to  the 
engine  cylinder.  On  the  other  hand,  an  engine  too  large  for  the 
work  it  has  to  do  will  give  poor  fuel  economy. 

As  the  economy  is  very  nearly  independent  of  the  size  of  the 
gas  engine,  it  is  better  to  buy  two  small  engines  than  one  large 
one.  This  applies  especially  to  the  farm,  where  the  larger  engine 
of  6  to  10  h.p.  can  be  used  for  the  heavier  work  such  as  feed 
grinding,  threshing,  wood  sawing,  etc.,  and  a  small  engine  of 
about  2  h.p.  for  the  many  small  tasks,  about  the  house,  dairy 


Fig.  141. 

and  barn,  which  require  but  little  power.  An  engine  of  2  h.p. 
is  sufficient  to  drive  a  small  dynamo,  light  the  house,  barn,  etc., 
and  charge  a  storage  battery  (see  Chapter  X) .  The  same  engine, 
if  portable,  can  be  used  for  driving  a  washing  machine  and 
wringer,  a  tree  sprayer  outfit,  a  house  pump,  cream  separator, 
etc.  i 

An  engine  governed  by  the  hit-or-miss  principle  should  carry 
such  a  load  as  will  enable  it  to  miss  one  explosion  in  every  eight, 
as  this  will  keep  the  cylinder  free  from  inert  burned  gases  and 
will  improve  the  economy.     If  an  engine  is  worked  at  its  maxi- 


GAS  AND  OIL  ENGINES  133 

mum  power  the  largest  part  of  the  time  the  wear  on  the  parts 
will  be  too  great. 

An  engine  for  farm  use  must  be  capable  of  being  started 
easily  and  should  be  simple  in  construction.  Every  gas  engine 
must  have  certain  parts  to  carry  out  the  cycle  of  operations, 
as  explained  in  the  earlier  part  of  this  chapter,  but  some  engines 
are  provided  with  many  attachments,  which  have  good  points, 
but  complicate  the  engine  so  that  the  first  cost  is  greater  and  the 
manipulation  more  difficult.  An  engine  to  be  of  value  on  the 
farm  must  be  sufficiently  simple  in  construction  so  that  ordinary 
adjustments  and  repairs  can  be  made  without  the  aid  of  experts. 

In  regard  to  the  method  of  igniting  the  mixture,  the  electric 
system  is  best  for  gasoline  engines.  It  is  well  to  provide  a  gaso- 
line engine  with  a  magneto  or  ingition  dynamo,  as  with  batteries 
the  cost  of  upkeep  is  considerable  and  the  reliability  of  opera- 
tion uncertain.  Regarding  drives  for  magnetos,  friction  and 
belt  drives  should  not  be  selected,  as  they  are  not  reliable.  A 
magneto  should  always  be  positively  driven  from  the  engine  by 
gears. 

There  is  very  little  choice  between  the  jump-spark  and  the 
make-and-break  systems  of  ignition.  For  stationary  engines 
the  make-and-break  is  commonly  used  while  the  jump-spark  is 
more  common  on  automobiles  and  traction  engines.  No  matter 
which  system  of  electric  ignition  is  selected,  the  various  wires 
should  be  well  insulated,  and  enclosed  in  some  moisture-proof 
conduit. 

For  irrigation  work  where  the  cost  of  fuel  is  an  important  item, 
an  engine  should  be  selected  which  will  operate  with  the  cheaper 
fuels.  For  engines  under  100  h.p.,  those  which  will  burn  solar 
oil  will  usually  be  found  satisfactory.  Such  engines  employ 
electric  ignition  and  the  fuel  is  vaporized  in  a  coil  entirely  out- 
side of  the  engine  cylinder.  For  work  requiring  100  h.p.  and 
more  the  various  engines  with  automatic  ignition,  which  use  the 
very  heavy  oils,  will  be  found  more  economical. 

It  is  essential  to  select  an  engine  from  a  reputable  manufacturer 
Every  engine  has  parts  broken  and  it  is  important  that  dupli- 
cate parts  may  be  easily  secured.  It  is  also  well  to  investigate 
the  work  done  by  engines  of  various  makes  before  making  the 
final  selection. 


134  FARM  MOTORS 

The  rated  horse-power  of  an  engine  does  not  often  mean  the 
same  actual  power  for  different  makes  of  engines.  An  engine 
rated  at  10  h. p.  by  one  manufacturer  may  be  capable  of  develop- 
ing 10  to  25  per  cent,  more  power  than  an  engine  of  the  same 
rating  by  another  manufacturer.  The  purchaser  should  insist 
on  a  definite  statement  as  to  the  actual  brake  horse-power 
which  the  engine  is  capable  of  developing.  The  method  of 
obtaining  the  brake  horse-power  of  an  engine  was  explained  in 
Chapter  II. 

Installation  of  Gas  Engines. — It  is  usually  best  to  locate  a 
gas  engine  in  a  separate  room.  The  room  should  be  well  lighted 
and  ventilated,  free  from  dirt  and  dust  and  should  be  large 
enough  so  that  there  would  be  sufficient  space  for  easy  access  to 
any  part  of  the  engine  so  as  to  facilitate  starting,  oiling  and  in- 
spection of  all  parts. 

In  connection  with  gasoline  and  oil  engines,  the  fuel  tank 
should  be  located  outside  of  the  building  and  preferably  under- 
ground. In  any  case  the  tank  must  be  lower  than  the  pipe  to 
which  it  is  connected  in  the  engine  room. 

As  the  mixture  of  fuel  and  air  is  ignited  inside  the  engine 
cylinder,  the  resulting  explosion  produces  a  shock  of  considerable 
magnitude  on  the  mechanism,  which  in  turn  is  transmitted  to 
the  foundation.  The  foundation  should  be  as  solid  as  possible. 
If  the  engine  is  to  be  set  on  a  wood  floor,  it  is  usually  well  to  lay 
long  timbers  on  or  under  the  floor  and  at  right  angles  to  the 
joists.  If  the  foundation  is  to  be  built  of  brick  or  of  concrete 
it  should  be  sufficiently  heavy  and  should  be  separated  from  the 
walls  of  the  building,  so  that  vibrations  caused  by  the  engine 
will  not  affect  the  building  or  surrounding  buildings.  If  the 
engine  has  to  be  located  over  another  room  it  is  best  to  place  the 
engine  in  a  corner  and  near  the  wall. 

The  method  of  constructing  foundations  for  steam  engines  was 
explained  in  detail  in  Chapter  V.  The  directions  given  there 
apply  also  to  gas  engines. 

If  the  engine  is  to  be  connected  to  the  machines  to  be  driven 
by  belt  drive,  the  driver  and  driven  should  be  placed  far  enough 
apart,  so  that  the  required  power  can  be  transmitted  without 
running  the  belts  too  tight.  A  distance  between  pulleys  equal 
to  about  eight  times  the  size  of  the  larger  pulley  will  usually  give 


GAS  AND  OIL  ENGINES  135 

good  results.     Open  belts  are  preferable  to  crossed   belts  and^ 
should  be  used  whenever  possible. 

The  exhaust  piping  should  be  as  straight  and  as  short  as  pos- 
sible. The  exhaust  gases  should  always  be  discharged  out  of 
doors,  as  the  fumes  are  poisonous.  Some  engines  are  provided 
with  exhaust  mufflers  (Fig.  117)  which  can  be  located  near  the 
engine.  As  a  rule  it  is  better  to  locate  the  muffler  outside  of  the 
building.     Engines  should  never  exhaust  into  a  flue  or  chimney. 

The  air  supply  can  be  taken  from  the  room  in  which  the  engine 
is  placed  or  from  the  outside.  In  all  cases  a  screen  should  be 
placed  over  the  air  pipe. 

Instructions  for  Starting  Gas  Engines. — Before  an  engine  is 
started  for  the  first  time,  all  the  working  parts  should  be  care- 
fuUy  examined  and  nuts  and  other  fasteners  properly  tightened. 
The  electrical  connections  should  then  be  gone  over  and  the  spark 
plug  or  spark  points  removed  from  the  cylinder  and  tried.  The 
various  valves  should  then  be  set  to  operate  at  the  proper  time. 
The  inlet  valve  should  open  just  before  the  piston  starts  on  its 
suction  stroke.  The  exhaust  valve  should  open  when+the  piston 
is  very  near  the  end  of  the  expansion  stroke  and  should  remain 
open  until  the  crank  is  about  10  degrees  before  the  completion 
of  the  exhaust  stroke.  The  ignition  should  be  timed  so  that  the 
spark  occurs  at  a  crank  position  of  about  15  degrees  before  the 
end  of  the  compression  stroke. 

The  gas  engine  is  not  self  starting,  as  is  the  steam  engine  when 
steam  is  turned  on.  The  reason  for  this  is  that  the  explosive 
mixture  of  fuel  and  air  must  be  taken  into  the  cylinder  and  com- 
pressed before  it  can  give  up  its  energy  by  explosion.  It  is, 
therefore,  necessary  to  set  the  engine  in  motion  by  some  external 
means  not  employed  in  regular  operation,  before  it  will  pick  up 
the  normal  working  cycle.  Engines  under  20  h.p.  are  usually 
started  by  hand.  This  is  done  by  disconnecting  the  engine 
from  its  load  aJnd  turning  the  flywheel  by  hand  for  a  few  revolu- 
tions. If  everything  is  in  good  condition  an  engine  should  start 
with  two  or  three  turns  of  the  flywheel  and  should  continue  to 
run  after  the  flrst  explosion.  An  easier  method  of  starting  gaso- 
line engines  is  by  injecting  some  gasoline  into  the  cylinder 
through  a  priming  cock,  turning  the  flywheel  against  compression 
as  far  as  possible  and  then  quickly  tripping  the  igniter. 


136  FARM  MOTORS 

As  it  is  difficult  to  pull  over  an  engine  by  hand  against  com- 
pression throughout  the  whole  stroke,  most  engines  are  provided 
with  a  starting  cam,  which  can  be  shifted  so  as  to  engage  the 
exhaust  valve  lever.  This  relieves  the  compression  while  crank- 
ing, as  the  exhaust  port  is  open  during  the  first  part  of  the  com- 
pression stroke.  After  the  engine  speeds  up  the  starting  cam 
is  disengaged. 

Gas  engines  larger  than  25  h.p.  are  usually  started  with  com- 
pressed air.  If  the  engine  consists  of  two  or  more  cylinders, 
this  can  be  accomplished  by  shutting  off  the  gas  supply  to  one 
of  the  cylinders  and  running  this  cylinder  with  compressed  air 
from  a  tank,  in  the  same  manner  as  a  steam  engine  is  operated 
with  steam  from  a  boiler.  As  soon  as  the  other  cylinders  pick 
up  their  cycle  of  operations  the  compressed  air  is  shut  off  and 
fuel  with  air  is  admitted  to  the  cylinder  used  in  starting.  With 
large  gas  engines  of  only  one  cylinder,  the  compressed  air  is  ad- 
mitted long  enough  to  start  the  engine  revolving,  when  the  com- 
pressed air  is  shut  off  and  the  mixture  is  admitted.  The  air  supply 
for  starting  is  kept  in  tanks  which  are  charged  to  a  pressure  of 
50  to  150  lb.  by  a  small  compressor,  driven  either  from  the  main 
engine  shaft,  or  by  means  of  an  auxiliary  small  engine. 

In  starting  a  gas  engine  the  following  steps  should  be  taken, 
preferably  in  the  order  given: 

1.  The  fuel  supply  should  be  examined.  Cases  have  been 
known  in  which  an  operator  spent  considerable  time  hunting  for 
faults  in  the  ignition  system,  valve  setting,  etc.,  when  an  examina- 
tion of  the  gasoline  tank  would  have  revealed  the  fact  that  it  was 
empty. 

2.  The  ignition  system  should  be  tried  by  closing  the  switch 
disconnecting  the  end  of  one  of  the  wires  and  brushing  it  against 
the  binding  post  to  which  the  other  wire  is  attached.  A  good 
spark  should  have  a  blue  white  color.  If  the  spark  produced  is 
weak  the  ignition  system  should  be  put  in  the  proper  condition. 

3.  The  lubricators  and  grease  cups  should  be  filled  and 
adjusted,  so  that  the  proper  amount  of  oil  is  delivered  to  all 
bearings  and  moving  parts. 

4.  The  load  should  be  disconnected  from  the  engine  by  means 
of  a  friction  clutch  or  similar  device,  the  lubricators  turned  on, 
the  spark  retarded  to  the  starting  position,  and  the  starting  cam 
moved  in  place. 


GAS  AND  OIL  ENGINES  137 

5.  The  engine  is  now  ready  for  starting  by  either   of  the_ 
methods  previously  explained.     In  cranking,  always  pull  up  on 
the  crank. 

6.  As  soon  as  engine  picks  up,  disengage  starting  cam,  turn  on 
cooling  water,  advance  spark  to  running  position  and  throw  on 
the  load  by  means  of  the  clutch. 

7.  Adjust  fuel  supply  so  that  the  engine  carries  its  load  with 
the  cleanest  possible  exhaust. 

To  stop  an  engine,  the  fuel  valve  is  closed,  the  ignition  system 
switch  opened,  the  lubricators  and  oil  cups  are  closed  and  the 
jacket  water  is  turned  off.  In  cold  weather  the  water  should  be 
drained  from  the  engine  jackets  to  prevent  freezing.  The  prac- 
tice of  draining  the  jackets  is  also  advisable  in  moderate  weather 
as  this  tends  to  clean  the  jacket  from  the  deposit  of  sediment. 
Before  leaving  the  engine  it  should  be  cleaned,  all  parts  examined 
and  put  in  order  ready  for  starting  up. 

Causes  of  Gas  Engines  Failing  to  Start. — Failure  to  start  may  be 
due  to  one  or  more  of  the  following  causes : 

1.  Ignition  System  Out  of  Order. — This  may  be  caused  by  the 
switch  being  left  open,  by  a  loose  terminal,  by  a  disconnected 
wire,  by  a  broken  wire  the  insulation  being  intact,  by  the  ignition 
battery  being  weak  if  a  battery  is  used,  and  by  poor  timing  or 
wrong  connections  if  a  magneto  is  employed.  Other  causes  of 
faulty  ignition  are  due  to  timer  slipping  on  the  shaft,  to  a  short 
circuit  in  the  ignition  system,  to  carbonized  or  broken  spark 
points,  to  poor  timing  of  the  points  of  ignition.  In  the  case  of  the 
jump  spark  system,  ignition  will  also  be  prevented  if  the  points 
on  the  spark  plug  are  too  far  apart,  the  insulation  on  secondary 
wires  is  poor,  induction  coil  windings  are  broken  or  short- 
circuited,  vibrator  of  induction  coil  not  properly  set. 

2.  An  engine  will  not  start  if  the  mixture  contains  too  much 
or  too  little  fuel. 

In  very  cold  weather  a  gasoline  engine  may  give  trouble  by  the 
fuel  not  vaporizing.  This  can  best  be  remedied  by  filling  the 
jackets  with  hot  water. 

Improper  mixture  may  be  caused  by  slow  cranking,  in  which 
case  the  hand  placed  over  the  air  inlet  will  often  start  the  engine. 
Extra  priming  of  the  carbureter  may  also  aid  in  starting,  provided 
care  is  taken  not  to  flood  the  engine  with  fuel. 


138  FARM  MOTORS 

3.  Supply  pipes  clogged. 

4.  Dirt  or  water  in  the  fuel. 

5.  Pump  or  carbureter  out  of  order. 

6.  Water  in  carbureter. 

7.  Water  in  the  cylinder  due  to  leaky  jacket. 

8.  Inlet  valve  poorly  set  or  not  operating  due  to  broken  valve 
stem,  weak  or  broken  spring,  valve  sticking  or  broken. 

9.  Poor  compression  due  to  leaky  or  broken  piston  rings, 
improper  seating  of  valves,  or  to  other  leaks  from  the  cylinder  to 
the  outside. 

10.  If  the  exhaust  pipe  or  muffler  are  clogged  the  engine  will 
fail  to  start. 

In  any  of  the  above  cases  the  remedies  are  self-evident. 
Causes  of  Motor  Failing  to  Run. — A  motor  will  sometimes  start, 
but  will  soon  afterward  slow  down  and  stop.     This  may  be  due  to : 

1.  Fuel  tank  being  empty  or  fuel  pipe  becoming  clogged. 

2.  Poor  or  insufficient  lubrication,  which  may  cause  the  seizing 
of  the  piston  or  of  the  bearings. 

3.  Wire  being  jarred  loose  from  its  terminal,  timer  slipping  on 
shaft  or  to  some  other  fault  in  the  ignition  system,  such  as  weak 
cells,  or  vibrator  or  induction  coil  becoming  stuck. 

4.  Engine  carrying  too  great  a  load. 

Running  a  Gas  Engine. — It  is  best  to  keep  one  man  respon- 
sible for  the  care  of  an  engine.  The  engine  should  be  kept  clean 
and  all  the  parts  should  be  examined  frequently  to  see  that 
everything  is  in  the  best  working  order. 

If  an  engine  runs  well  at  no  load  but  will  not  carry  its  rated 
load,  this  may  be  due  to :  poor  compression,  poor  fuel,  defective 
ignition,  poor  timing  of  ignition,  incorrect  valve  setting,  incorrect 
mixture,  leaky  inlet  or  exhaust  valves,  too  much  friction  at  bear- 
ings, or  to  engine  being  too  small  for  the  rated  load. 

The  operator  can  usually  tell  as  to  whether  the  correct  mixture 
is  being  admitted  into  the  cylinder  by  watching  the  exhaust. 
Black  smoke  issuing  from  the  exhaust  pipe  means  that  the  mix- 
ture is  too  rich  in  fuel.  This  should  be  remedied  by  decreasing 
the  amount  of  fuel  supplied  or  by  increasing  the  air  supply. 
Insufficient  fuel  in  the  mixture,  as  explained  in  the  section  on 
Carbureters,  will  cause  the  engine  to  miss  explosions  and  may 
even  cause  backfiring. 


GAS  AND  OIL  ENGINES  139 

Premature  ignition,  often  called  preignition,  is  due  to  the_de^ 
position  of  carbon  and  soot  on  the  walls  of  the  cylinder,  the  com- 
pression being  too  high  for  the  fuel  used,  by  overheating  of  the 
piston,  exhaust  valve  or  of  some  poorly  jacketed  part. 

Deposition  of  carbon  on  the  cylinder  walls  is  usually  caused 
by  the  use  of  either  an  excessive  amount  or  of  a  poor  quality  of 
lubricating  oil.  This  will  not  only  cause  preignition,  but  may 
also  impair  the  action  of  the  valves,  igniter  and  piston  rings. 
Carbon  deposits  will  also  be  produced  if  the  mixture  is  too  rich. 

Insufficient  lubrication  may  result  in  abrading  surfaces  of 
piston  and  cylinder. 

It  is  well  not  to  economize  when  buying  gas  engine  cylinder 
oil.  Due  to  the  high  temperatures  developed  inside  of  the  engine 
cylinder  and  to  the  absence  of  moisture,  a  cylinder  oil  should  be 
selected  which  is  light  and  thin,  which  will  withstand  high  tem- 
peratures and  will  leave  no  carbon  deposits.  A  cylinder  lubricat- 
ing oil  well  suited  for  steam  engine  use  will  not  do  at  all  for  gas 
engine  cylinder  lubrication. 

For  the  bearings  and  other  rubbing  parts  outside  of  the 
cylinder,  a  good  grade  of  machine  oil  will  be  found  satisfactory. 

A  blue  smoke  at  the  exhaust  indicates  that  too  much  cylinder 
oil  is  being  used. 

Pounding  in  gas  and  oil  engines  is  either  due  to  preigni- 
tion, the  causes  of  which  were  outlined  above,  to  lost  motion  in 
some  bearing  of  the  engine,  or  to  the  engine  being  loose  on  its 
foundation. 

In  the  case  of  oil  engines  using  a  water  spray  with  the  fuel,  too 
little  water  will  result  in  preignition  and  consequent  pounding. 
This  should  be  remedied  by  supplying  more  water  with  the  fuel. 
Too  much  water  will  be  indicated  by  white  smoke  issuing  from 
exhaust  pipe. 

In  the  case  of  a  gasoline  engine,  white  smoke  at  the  end  of  the 
exhaust  pipe  usually  indicates  water  in  the  gasoline,  which  may 
be  due  to  a  leaky  jacket  or  to  some  other  cause. 

In  regard  to  the  temperatures  of  the  jacket  water,  this  depends 
on  the  compression  carried  and  on  the  size  of  the  engine.  With 
small  engines  of  the  hopper-cooled  type  the  jacket  temperature 
is  near  the  boiling  point  of  water.  Ordinarily  a  temperature  of 
about  150°  F.  will  give  good  results. 


CHAPTER  VII 
TRACTION  ENGINES  AND  AUTOMOBILES 

Traction  Engines 

Fundamental  Parts  of  a  Traction  Engine. — A  steam  or  a  gas 
engine,  explained  in  the  previous  chapters,  can  be  converted 
into  a  traction  engine  by  mounting  it  on  trucks  and  providing 
additional  mechanisms,  so  that  the  engine  will  not  only  be 
capable  of  producing  rotation  at  a  shaft,  but  will  also  move  itself 
over  fields  and  highways,  thus  performing  the  work  of  many 
horses  in  a  cheaper,  quicker  and  better  manner. 

All  traction  engines  must  consist  of  the  following  fundamental 
parts : 

1.  Some  Form  of  Motor. — This  in  the  case  of  steam  traction 
engines  consists  of  an  engine  and  boiler.  Gas  traction  engines 
employ  an  internal  combustion  engine  burning  gasoline,  kerosene 
or  solar  oil. 

2.  Engine  Accessories. — Steam  traction  engine  accessories 
include  valves  and  piping  from  boiler  to  engine,  fuel  hopper, 
water  tank,  safety  valve,  water  glass,  steam  gage,  blow  off, 
pump  or  injector  or  both,  a  stack  and  spark  arrester.  Some 
steam  traction  engines  have  also  a  feed  water  heater  which  heats 
with  exhaust  steam  the  feed  water  before  it  enters  the  boiler. 
The  accessories  of  the  gas  traction  engine  are  fuel  tanks,  water 
tanks,  batteries  and  battery  boxes,  magnetos,  carbureters. 

3.  Reversing  Mechanism. — Reversing  of  a  steam  traction 
engine  is  accomplished  either  by  a  link  similar  to  that  used  in 
locomotive  practice,  or  by  some  form  of  single  eccentric  radial 
valve  gear.  It  is  more  difficult  to  reverse  a  gas  traction  engine 
and  a  train  of  gears  must  be  employed. 

4.  Steering  Mechanism. 

5.  Transmission  Mechanism. — The  speed  of  the  engine  is 
too  great  for  direct  utilization,  and  a  train  of  gears  must  be 
interposed  between  the  engine  and  drive  wheels. 

140 


TRACTION  ENGINES  AND  AUTOMOBILES      141 

6.  Differential  or  Compensating  Gear. — The  purpose  of  this^  is^ 
to  allow  one  drive  wheel  to  revolve  independently  of  the  other, 
this  being  necessary  when  turning  corners,  as  will  be  explained 
later. 

7.  Friction  clutch  for  disengaging  engine  from  propelling  gear, 
so  that  the  power  of  the  engine  can  be  utilized  for  the  driving  of 
separators  or  other  machinery.  Some  makes  have  no  friction 
clutch. 

8.  Trucks  for  mounting  engine  and  other  parts. 

9.  Traction  or  drive  wheels  (Figs.  145  and  146),  which  must 
be  provided  with  lugs  to  give  them  a  firm  footing  on  the  ground, 
and  with  mud  shoes. 


Fig.  142. 

10.  Front  Wheels. — These  are  made  smaller  and  lighter  than 
the  traction  wheels,  and  are  provided  with  a  smooth  tire.  To 
prevent  skidding  the  front  wheels  are  built  with  a  flange  in  the 
center  (Figs.  145  and  146).  The  front  wheels  turn  upon  an 
axle  which  is  attached  to  a  ball  and  socket  joint,  or  to  some 
similar  mechanism,  so  as  to  allow  for  uneven  ground  and  also  to 
facilitate  steering. 

Steam  Traction  Engines. — The  boiler  of  the  steam  traction 


142 


FARM  MOTORS 


engine  is  internally  fired.     Some  builders  utilize  the  return  flue 
type  (Fig.  142),  others  a  locomotive  type  (Fig.  143). 


■ 

w , 

,>--'^^.^-^.y     .\.  :,                                           ,.!f      ■•  ^ 

t 

?-^-  .:    I 

,        ,-ir                               ;  :  .  :  ■r^.^SsifflaMfflST^- 

,,;......■:■.■:::■■::■_          V 

•  ■' — ...   «■"•"""' jyy 

■»-         ^ 

■■L        ' 

Fig.  143. 


Fig.  144. 


When  using  straw  for  fuel,  the  furnace  is  modified  as  shown  in 
Fig.  144.  Slab  grates  are  then  substituted  for  the  ordinary  coal 
grates  and  the  straw  is  fed  through  a  chute  S.     A  hinged  trap 


TRACTION  ENGINES  AND  AUTOMOBILES       143 

T  is  provided  to  prevent  the  entrance  of  air  when  the  straw Js^ 
not  being  fed. 


Fig.  145. 


Fig.  146. 


In  some  makes  of  traction  engines,  the  boiler  is  mounted  upon 
the  truck  and  is  used  as  the  foundation  for  the  engine  (Fig.  145). 


144 


FARM  MOTORS 


Other  types   (Fig.   146)   have  the  engine  mounted  under  the 
boiler,  the  frame  supporting  both  engine  and  boiler. 

Two  types  of  feed  pumps  are  used  on  steam  traction  engines : 


Fig.  147. 


The  independent  pump  which  is  similar  to  the  types  illustrated 
in  Chapter  IV.  Some  traction  engines  use  a  cross-head  pump  P 
(Fig.  147),  which  is  driven  from  the  engine  cross-head  C.     As 


mSBHKKM-H 


Fig.  148. 


in  the  case  of  stationary  engines,  two  independent  methods 
should  be  employed  for  feeding  water  into  a  traction  engine 
boiler,  using  either  two  pumps  or  an  injector  and  a  pump. 


TRACTION  ENGINES  AND  AUTOMOBILES      145 

Feed  water  heaters  are  used  on  some  traction  engines.  T^ 
type  often  employed  is  illustrated  in  Fig.  148.  The  feed  water 
passes  through  the  annular  space  between  the  tubes  and  the 
exhaust  steam  surrounds  the  tubes. 


Fig.  149. 


Fig.  150. 


Traction  engines  using  wood  or  straw  are  usually  provided 
with  some  form  of  spark  arrester.  This  consists  of  a  screen  dome 
placed  over  the  stack,  or  of  some  arrangement  for  deflecting  the 
smoke,  so  that  the  sparks  will  be  deposited  in  water. 


10 


146 


FARM  MOTORS 


The  type  of  engine  employed  is  some  simple  form  of  steam 
engine  with  a  slide  valve.  Some  traction  engines  have  double- 
cylinder  engines.    Compound  engines  are  also  used  to  some  extent. 

The  details  of  the  engines,  governors  and  accessories  do  not 
differ  from  those  described  in  chapter  V. 

A  steam  traction  engine  can  be  reversed  either  by  a  Stephenson 
link  similar  to  that  used  on  locomotives,  or  by  some  form  of  single 
eccentric  radial  valve  gear. 


Fig.  151. 


To  reverse  an  engine  by  means  of  the  Stephenson  link,  it 
must  be  provided  with  two  eccentrics,  placed  opposite  to  each 
other  on  the  crank  shaft,  each  being  connected  by  an  eccentric 
rod  to  the  end  of  a  link.  A  block  connected  to  the  valve  shdes 
along  a  groove  in  the  link. 

This  type  of  reversing  link  as  applied  to  a  traction  engine  is 
illustrated  in  Fig.  149.  The  two  eccentrics  shown  at  E  are 
attached  to  the  curved  link  L  by  means  of  the  eccentric  rods  A 
and  B.  The  position  of  the  link  is  varied  by  the  reverse  lever 
through  the  reach  rod  R.     In  one  position  of  the  link  the  motion 


TRACTION  ENGINES  AND  AUTOMOBILES      147 

to  the  valve  is  given  by  one  eccentric,  driving  the  shaft  in  one 
direction.  This  direction  of  rotation  is  reversed  by  raising  the 
link,  so  that  the  valve  receives  motion  from  the  other  eccentric. 
If  the  reverse  lever  is  moved  so  that  the  block  is  in  the  middle 
of  the  link,  the  motion  given  by  both  eccentrics  will  be  equal 
and  opposite,  and  the  valve  will  have  no  motion. 

Most  traction  engines  employ  a  single  eccentric  radial  valve 
gear  (Fig.  150).  This  reversing  gear  consists  of  an  eccentric  B 
fastened  on  the  crank  shaft.     The  eccentric  strap  has  an  extended 


Fig.  152. 


arm  C,  pivoted  in  a  block  E,  which  slides  up  and  down  in  a 
guide  F,  and  gives  motion  to  the  rod  D,  which  is  transmitted 
to  the  valve  through  the  rocker  K  and  valve  stem  J.  The  guide 
F  is  hung  on  a  trunnion  and  it  can  be  tilted  in  any  direction  by 
the  reverse  lever  R.  The  angle  at  which  the  guide  F  is  set 
determines  the  direction  in  which  the  engine  is  to  run.  The 
quadrant  Q  is  usually  provided  with  three  notches.  When  the 
reverse  lever  is  in  the  central  notch  no  motion  is  given  by  the 


148 


FARM  MOTORS 


block  E  to  the  valve  rod  J.  In  the  position  shown,  the  block 
E  sliding  up  and  down  in  the  guide  F  moves  the  valve  in  one 
direction.  Placing  the  reverse  lever  in  the  notch  at  the  ex- 
treme right  reverses  the  engine. 

Steering  is  accomplished  by  turning  the  front  axle.  This  is 
done  by  chains  C  (Fig.  151)  which  wincj  upon  a  spool.  The 
spool  is  operated  by  hand  through  a  worm  W  and  pinion  P 
(Fig.  151).     Another  method  is  to  operate  a  screw  by  the  worm 


Fig.  153. 


and  pinion,  the  screw  moving  a  nut  which  is  connected  by  a 
system  of  levers  to  the  front  axle.  In  large  traction  engines 
steering  is  accomplished  by  power  furnished  by  the  engine 
through  a  friction  disc. 

A  friction  clutch,  the  function  of  which  is  to  disengage  the 
engine  from  the  propelling  gear,  is  illustrated  in  Fig.  152.  The 
flywheel  W  is  fixed  to  the  engine  shaft,  and,  when  used  as 
a  belt  wheel,  it  is  not  connected  to  the  arm  C,  and  thus  does 


TRACTION  ENGINES  AND  AUTOMOBILES      149 


Fig.  154. 


Fig.  155. 


150  FARM  MOTORS 

not  transmit  motion  to  the  pinion  F  which  is  rigidly  connected 
with. the  arms  C.  When  the  clutch  is  thrown  in,  pressure  is 
applied  at  E  which  rests  in  a  groove  in  the  piece  D.  This 
results  in  B  crowding  the  shoe  A  against  the  inner  rim  of 
the  flywheel.  The  friction  clutch  has  two  shoes  made  of  wood 
or  of  some  other  yielding  material  AA,  which  press  against  the 
inner  rim  of  the  flywheel  when  the  clutch  is  thrown  in,  and  this 
transmits  the  motion  of  the  engine  through  the  arms  C  and  pinion 
F  to  the  transmission. 


Fig.  156. 

The  transmission  mechanism  (Fig.  153)  delivers  the  power 
from  the  engine  to  the  traction  wheels  which  must  revolve 
slower  than  the  engine  crank  shaft.  The  gear  A  receives  motion 
from  the  engine  and  delivers  this  through  the  train  of  gears  to 
the  gear  B,  which  is  connected  to  the  traction  wheel. 

Differentials  for  Traction  Engines. — When  a  traction  engine 
turns  a  corner,  the  drive  wheel  on  the  outside  of  the  curve  must 
turn  faster  than  that  on  the  inside.  If  the  two  drive  wheels 
were  rigidly  connected,  one  would  have  to  skid  or  slip,  when 
turning  a  corner,  and  this  would  throw  a  great  strain  on  the 
wheels  and  axles.  The  differential,  sometimes  called  a  com- 
pensating gear,  allows  one  drive  wheel  to  move  ahead  of  the  other. 


TRACTION  ENGINES  AND  AUTOMOBILES       151 


a 

^^^^r^J/f^tf^ 

^  ^--^^^-^i^ 

Fig.  157. 


Fig.  158. 


152 


FARM  MOTORS 


Fig.  159. 


Fig.  160. 


TRACTION  ENGINES  AND  AUTOMOBILES      153 

The  differential  can  be  placed  between  the  two  drive  wheels^ou 
the  rear  axle.  A  more  common  method  is  to  have  the  differential 
on  a  separate  shaft,  the  traction  wheels  being  driven  from  that 
shaft  by  means  of  pinions. 

The  principle  of  differentials  as  applied  to  steam  and  gas 
traction  engines  is  illustrated  in  Figs.  154  and  155.     The  differ- 


■ 

■■■■ 

■P 

H 

^H 

H^^B^^^^^H 

[W''3^ 

^M 

B^^^^^B^^M 

V^B^i 

mg'^m 

1 

r 

__-  ^P'^^ 

^ii 

^ 

'i 

i 

■llfl 

I 

i 
1 

„'■•""'"  -J 

1 

^ 

I. 

1 

t( 

1 

m 

1 

w^^^^^ 

f^jm'*^-* 

Fig.  161. 

ential  shaft  S  consists  of  two  shafts,  each  being  connected 
either  directly  or  through  gears  to  the  drive  wheels.  Two  bevel 
gears  C  and  D  are  keyed  to  those  two  differential  shafts  and 
engage  several  bevel  pinions,  marked  B,  which  turn  freely  on 
their  respective  shafts.    The  power  from  the  engine  is  trans- 


154 


FARM  MOTORS 


TRACTION  ENGINES  AND  AUTOMOBILES      155 

mitted  through  the  pinion  P  to  the  large  spur  gear  A.  When 
the  engine  is  going  ahead  on  a  level  road  and  both  drive 
wheels  are  rotating  at  the  same  speed,  the  two  bevel  gears  C 
and  D  will  also  revolve  at  the  same  speed  and  the  small  pinions 
marked  B  will  remain  stationary.  In  turning  a  corner  or  in 
meeting  some  obstruction,  if  the  drive  wheel  connected  to  C 
moves  slower  than  that  connected  to  D,  the  pinions  B  will 
revolve  on  the  bevel  gear  D  at  a  faster  rate.     In  other  words, 


lar^m 

M      ^-'' 

**■■■■■  ««*i»^-« .  \' 

Fig.  163. 


the  difference  in  motion  between  the  two  drive  wheels  is 
compensated  for  by  the  revolution  of  the  pinions  B. 

Another  gas  traction  engine  differential  is  shown  in  Fig.  156, 
the  letters  designating  the  same  parts  as  in  Figs.  154  and  155. 
The  two  pinions  E  and  F  connect  the  differential  with  the  two 
drive  wheels.  Bevel  gear  C  is  at  the  right  of  spur  gear  A.  W 
is  a  brake  wheel. 

Gas  Traction  Engines. — The  term  gas  traction  engines  is 


156 


FARM  MOTORS 


applied  to  such  as  are  propelled  by  internal  combustion  engines. 
The  fuels  most  commonly  used  are  gasoline,  kerosene  and  solar 
oil. 


ISS^ 

3H| 

-,y^ 

^m 

Fig.  164 


All  gas  traction  engines  use  internal  combustion  motors  work- 
ing on  the  four-stroke  Otto  gas  engine  cycle.     The  types  of  engines 


Fig.  165. — Reverse  gears. 

used  are  single  cylinder  (Fig.  157),  twin  cylinder  (Fig.  158),  two 

cylinder  opposed  (Fig.  159)  and  four  cylinder  motors  (Fig.  160). 

The  details  of  construction  of  the  engines  and  auxiliaries  are 


TRACTION  ENGINES  AND  AUTOMOBILES      157 

very  similar  to  those  of  stationary  gas  and  oil  engines  explainefirifr 
Chapter  VI. 

Some  gas  traction  engines  employ  the  make  and  break  system 
of  ignition  very  successfully.  The  majority,  however,  use  the 
jump  spark  system.  Magnetos  furnish  current  for  ignition. 
Some  makes  start  on  the  magneto,  but  the  majority  use  dry  or 
storage  batteries  for  starting. 

Both  the  hit  and  miss  and  the  throttling  systems  of  governing 
are  used,  the  hit  and  miss  system  being  more  common  in  the 
smaller  sizes  and  the  throttling  governor  in  larger  gas  traction 
engines. 


Fig.  166. 


Most  traction  engines  are  provided  with  two  fuel  tanks,  and 
are  built  to  operate  either  on  gasoline  or  on  kerosene.  When  using 
kerosene,  water  is  injected  with  the  fuel  to  prevent  preignition. 

Float  feed  carbureters  are  most  commonly  employed,  but  mixer 
valves  with  fuel  pumps  will  also  be  found,  similar  to  those  used  in 
connection  with  stationary  gasoline  engines.  Fig.  161  shows 
one  form  of  carbureter.  The  three  compartments  from  right  to 
left  are  for  gasoline,  water  and  kerosene.  The  lower  section  is  a 
mixing  chamber.  A  plate  controlled  by  the  governor  varies  the 
quantity  of  the  mixture  admitted. 

Some  engines  are  provided  with  an  auxiliary  relief  exhaust 


158 


FARM  MOTORS 


port  (Fig.  162).     The  advantages  claimed  for  this  are  that  the 
exhaust  valves  do  not  have  to  open  against  as  great  a  pressure 


Fig.  167. 


Fig.  168. 


and  that  the  hottest  gases  escape  through  the  relief  port  and  thus 
the  life  of  the  exhaust  valve  is  prolonged. 


TRACTION  ENGINES  AND  AUTOMOBILES       159 


Fig.  169. 


Fig.  170. 


160 


FARM  MOTORS 


Gas  traction  engines  are  either  water  cooled  or  oil  cooled,  and 
are  provided  with  a  radiator  (Fig.  162)  for  the  purpose  of  cooling 


Fig.  171. 


Fig.  172. 

the  water  or  oil  after  it  has  absorbed  heat  from  the  cylinder 
walls. 


TRACTION  ENGINES  AND  AUTOMOBILES      161 


Fig.  173. 


Fig.  174. 


162 


FARM  MOTORS 


As  in  steam  traction  engines,  steering  is  accomplished  by 
moving  the  front  wheels  (Figs.  163  and  164).  The  general  details 
of  the  transmission  train  (Fig.  163)  are  also  similar  to  those  of 
steam  traction  engines. 

The  engine  illustrated  in  Fig.  164  is  provided  with  two  clutches, 
one  for  forward  and  one  for  return.  Both  clutches  are  operated 
by  a  single  lever. 

Another  method  of  reversing  a  gas  traction  engine  is  shown  in 
Fig.  165.  Gear  A  is  located  on  the  clutch  shaft.  When  the 
engine  is  traveling  forward  gear  A  acts  directly  on  pinion  C.     To 


Fig.  175. 


reverse  the  engine  a  lever  slides  the  gear  A  out  of  mesh  with  the 
pinion  B  and  engages  it  with  pinion  C  which  meshes  with  B. 
Both  positions  are  illustrated  in  the  figure. 

Still  another  method  of  reversing  is  given  in  Fig.  166.  The  two 
bevel  pinions  A  and  B  are  free  on  the  transmission  shaft.  By 
moving  the  lever  L  to  the  right  bevel  pinion  B  engages  bevel  gear 
C  and  the  drive  is  in  one  direction.  To  reverse,  pinion  A  is 
shifted  by  the  lever  A  to  mesh  with  C,  pinion  C  gearing  with  B. 


TRACTION  ENGINES  AND  AUTOMOBILES      163 

The  other  details  of  gas  traction  engines,  such  as  the  clutch  fer 
changing  from  traction  to  belt  power,  construction  of  front  and 
traction  wheels,  are  very  similar  to  those  of  steam  traction 
engines. 

Uses  of  Traction  Engines. — A  traction  engine  can  be  used  for 
plowing,  seeding,  packing,  harrowing,  harvesting,  threshing,  hay- 
baling,  road  building,  ditch  digging  and  marketing.  Besides 
these  field  operations  it  can  do  most  of  the  work  of  a  stationary- 
engine.  Among  the  uses  of  a  traction  engine  on  belt  may  also  be 
mentioned  the  grinding  of  feed,  corn  shelling,  husking  and  shred- 
ding, ensilage  cutting,  silo  filling,  wood  sawing,  well  drilling,  rock 
crushing,  driving  cement  mixers  and  electrical  dynamos,  pumping 
water,  and  other  uses. 

The  small  traction  engine  illustrated  in  Fig.  167  is  designed 
for  moderately  small  farms  and  is  applicable  for  road  grading 
and  plowing.  It  may  also  be  used  for  pulling  harrows,  seeders, 
etc. 

With  a  traction  engine  the  processes  of  plowing,  seeding  and 
harrowing  can  be  carried  on  in  one  operation  (Fig.  168).  Plow- 
ing with  a  tractor  (Fig.  169)  is  done  deeper  and  more  uniformly 
than  is  the  case  with  animal  power.  Harvesting  with  steam  and 
gas  traction  engines  is  illustrated  in  Figs.  170  and  171.  The 
application  of  the  traction  engine  to  hay  bailing,  silo  filling  and 
road  building  is  illustrated  in  Figs.  172,  173  and  174.  A  traction 
engine  moving  a  barn  is  shown  in  Fig.  175. 

Rating  of  Traction  Engines. — Two  ratings  are  usually  given 
to  traction  engines.  The  first  is  in  brake  or  belt  horse-power. 
This  means  the  actual  power  developed  at  the  shaft  of  the  engine, 
which  can  be  utilized  for  driving  various  machines  by  means  of 
belt  drive. 

The  other  rating  is  in  traction  or  drawbar  horse-power.  To 
obtain  the  traction  horse-power  the  amount  of  power  lost  in 
transmission  to  the  drive  wheels  and  that  required  to  propel 
the  traction  engine  must  be  subtracted  from  the  brake  horse- 
power developed  at  the  shaft  of  the  engine. 

The  traction  horse-power  depends  on  the  kind  of  transmission 
gearing  and  on  the  character  of  the  roads  over  which  the  trac- 
tion engine  must  be  propelled.  It  is  equal  from  one-half  to  two- 
thirds  of  the  brake  horse-power.     As  an  illustration,  a  traction 


164  FARM  MOTORS 

engine  equipped  with  a  40  h.p.  engine  will  be  able  to  produce 
only  20  to  27  h.p.  at  the  draw-bar  under  ordinary  conditions. 

Management  of  Traction  Engines. — The  general  directions 
given  regarding  the  care  of  stationary  steam  and  gas  engines 
apply  also  to  the  motors  of  steam  and  gas  traction  engines. 
Bearing  surfaces  must  be  kept  well  lubricated  or  they  will  wear 
out,  and  lost  motion  in  bearings  should  be  avoided  to  prevent 
pounding  and  broken  crank  shafts. 

Before  taking  out  a  traction  engine  on  the  road,  it  should  be 
gone  over  carefully,  all  nuts  tightened,  bearings  properly  set, 
lubricators  filled,  and  clutch  adjusted  so  that  both  shoes  come  in 
contact  with  the  inside  of  the  wheel  at  the  same  time.  Boilers, 
engines  and  auxiliaries  should  be  working  properly.  If  possible 
enough  fuel,  water  and  oil  should  be  taken  for  the  days  run, 
so  as  to  avoid  delays. 

At  the  end  of  the  day's  run  the  engine  and  all  parts  should  be 
again  carefully  examined  to  see  that  every  bearing  gets  its  proper 
lubrication  and  runs  cool.  Every  oiler  and  grease  cup  should 
be  examined  and  filled.  Parts  such  as  connecting  rods  should 
be  tested  for  end  play.  The  valves  should  be  examined  for  wear. 
In  the  case  of  gas  traction  engines  it  may  be  necessary  to  grind 
the  exhaust  valves  about  every  two  weeks  during  the  heavy  sea- 
son, so  as  to  prevent  the  loss  of  compression  due  to  valve  leakage. 
This  is  done  with  oil  and  flour  emery  dust.  The  inlet  valves 
will  require  but  little  attention.  In  cold  weather  all  parts  should 
be  drained  to  prevent  freezing. 

In  operating  a  steam  traction  engine  on  the  road  the  boiler 
should  be  kept  with  water  to  the  proper  level.  This  is  best  done 
with  the  pump  forcing  the  water  through  the  feed-water  heater. 
The  injector  should  be  kept  in  reserve  for  emergencies.  The  fire 
should  be  kept  thin.  Care  must  be  taken  not  to  allow  the 
engine  to  remain  with  its  back  end  elevated  for  any  great  length 
of  time,  as  this  may  result  in  the  over-heating  of  the  crown  sheet. 
The  water  glass  should  be  blown  out  two  or  three  times  each 
day  and  the  safety  valve  should  be  kept  in  good  working  order. 

In  filling  the  fuel  tanks  of  gas  traction  engines,  the  fuel  should 
be  strained  through  a  fine  brass  screen  so  as  to  prevent  dirt 
from  getting  into  the  carbureter  and  supply  pipes  from  clogging. 

Traction  engine  cylinders  and  valves  should  be  cleaned  fre- 


TRACTION  ENGINES  AND  AUTOMOBILES      165 

quently  with  kerosene  so  as  to  remove  carbon  and  other  deposits.  - 
In  running  a  traction  engine  on  the  road,  the  operator  should 
keep  his  eyes  on  the  front  wheels  to  prevent  accidents.  In  case 
a  traction  engine  is  landed  in  a  hole,  it  can  be  pulled  out  by 
placing  chains,  boards  or  straw  under  the  drive  wheels.  The 
same  applies  when  the  engine  slips.  Before  crossing  a  bridge 
the  operator  should  ascertain  that  it  is  safe.  In  the  case  of  doubt, 
planks  should  be  placed  to  distribute  the  load. 

A  good  operator  handles  a  traction  engine  slowly  and  delib- 
erately, and  never  hesitates  to  stop,  should  something  go  wrong 
with  any  part  of  the  engine. 

In  laying  off  the  engine  for  the  winter,  it  should  be  placed  under 
cover  and  be  protected  from  rain  and  snow.  It  is  well  to  remove 
pistons  from  the  cylinders  of  gas  traction  engines,  clean  all  de- 
posits and  then  oil  pistons,  cylinders  and  valves  with  a  heavy  oil. 
Magnetos  and  batteries  should  always  be  removed  to  a  dry 
place.  All  parts  should  be  carefully  drained.  In  fact  it  is  well 
to  remove  all  drain  cocks  so  as  to  prevent  any  water  from 
remaining  in  cylinders  and  tanks. 

Automobiles 

Types  of  Automobiles. — An  automobile  can  be  propelled  by  a 
steam  engine,  by  an  internal  combustion  engine,  or  by  an  electric 
motor  with  current  secured  from  storage  batteries. 

The  majority  of  modern  automobiles  are  propelled  by  internal 
combustion  engines  using  gasoline  as  fuel. 

Steam  and  electric  cars  operate  more  quietly  arid  can  be  more 
easily  controlled  than  gasoline  cars.  Then  the  electric  car  has 
the  additional  advantages  of  cleanliness  and  ease  of  starting, 
while  the  steam  car  has  a  greater  range  of  power. 

To  offset  the  above  advantages,  electric  cars  are  more  expen- 
sive to  operate,  can  be  used  only  where  there  are  facilities  for 
charging  storage  batteries,  and  will  operate  only  on  runs  of 
about  one  hundred  miles,  before  they  have  to  be  recharged 

Steam  cars  require  considerable  time  to  start  after  a  long  stop, 
and  also  greater  skill  in  operating  than  gasoline  or  electric  cars. 

The  gasoline  automobiles  possess  also  the  additional  advan- 
tages, in  that  they  are  manufactured  in  many  different  types,  and 


166 


FARM  MOTORS 


can  be  secured  at  a  great  variety  of  prices,  from  several  hundred 
up  to  many  thousand  dollars  per  car. 

Most  of  the  modern  makes  of  gasoline  cars  are  supplied  with 
automatic  starters,  so  that  the  cars  may  be  started  from  the  seat. 
This  is  acccomplished  by  a  spring,  an  air  motor,  or  by  an  elec- 
tric motor. 

Gasoline  Automobiles. — The  general  details  of  an  automobile 
power  plant  are  illustrated  in  Fig.  176.     Most  automobiles  have 


Fig.  176. 

four-  or  six-cylinder  vertical  gasoline  engines  working  on  the 
four-stroke  Otto  gas-engine  cycle.  There  are  several  makes  of 
automobiles  using  the  two-stroke  cycle  engine.  Then  small  auto- 
mobiles are  sometimes  equipped  with  a  two-cylinder  or  even  single- 
cylinder  horizo'ntal  engine.  The  more  cylinders  are  employed, 
the  easier  it  is  to  start  and  to  run  an  automobile  slowly  without 
stopping. 

Automobile  engines  are  most  commonly  water  cooled  and  are 
provided  with  radiators,  the  purpose  of  which  was  explained  in 
connection  with  gas  traction  engines. 

Jump  spark  ignition  is  always  employed  in  automobiles  and 
most  modern  cars  are  provided  with  high-tension  magnetos. 

The  carbureters  are  of  the  float-feed  type  as  explained  in 
Chapter  VI. 

The  valve  shaft  is  usually  driven  by  gears  if  parallel  to  the 
crank,  and  by  a  worm  and  wheel  if  at  right  angles  to  the  shaft. 


TRACTION  ENGINES  AND  AUTOMOBILES      167 

The  poppet  type  of  valve  is  used  on  most  automobiles,  but-a 
slide  valve  has  recently  been  perfected  which  is  giving  excellent 
results. 

The  power  from  the  motor  crankshaft  is  delivered  to  the  fly- 
wheel which  forms  the  outer  part  of  the  clutch.  The  inner  part 
of  the  clutch  is  connected  to  the  transmission  and  speed-changing 
mechanism,  through  the  differential  and  to  the  drive  wheels. 
A  clutch  is  necessary  in  a  gasoline  automobile,  as  the  gasoline 
engine  cannot  be  started  under  load. 

A  transmission  and  speed-changing  train  must  be  provided 
between  the  clutch  and  drive  wheels  in  a  manner  similar  to  that 
explained  in  connection  with  gas  traction  engines.  The  trans- 
mission mechanism  consists  either  of  a  train  of  gears  or  of  friction 
discs. 

The  sliding-gear  system  of  transmission  is  most  commonly 
employed.  This  consists  of  an  auxiliary  shaft  which  is  con- 
nected to  the  drive  of  the  car  and  gears  with  the  engine  shaft. 
The  change  of  speeds  and  reversal  of  motion  is  accompHshed  by 
sliding  the  drive  gears  on  a  square  shaft. 

In  the  case  of  the  friction  drive  a  flat -faced  metal  disc  is  at- 
tached to  the  motor  crank  shaft.  The  other  part  is  a  wheel 
with  a  fiber  rim  keyed  to  a  shaft,  but  free  to  move  back  and  forth 
on  the  shaft.  This  shaft  is  mounted  parallel  to  the  face  of  the 
disc  wheel.  When  the  wheel  with  the  fiber  rim  is  near  the 
center  of  the  disc,  the  car  is  on  slow  speed.  The  farther  out 
from  the  center  this  wheel  is  shifted  the  faster  is  the  speed. 
If  this  wheel  is  shifted  across  the  center,  the  car  travels  back- 
ward. A  friction  drive  applied  to  an  automobile  is  illustrated 
in  Fig.  266,  Chapter  XI. 

The  automobile  differential  works  on  the  same  principle  and 
serves  the  same  purpose  as  the  differential  of  traction  engines. 
It  differs  from  the  traction  engine  differential,  in  that  it  is  en- 
tirely enclosed,  and  that  the  train  of  gears  for  speed  charging  is  at 
another  place. 

Automobile  Troubles  and  Their  Remedies. — In  Table  6  will 
be  found  some  of  the  more  common  causes  of  automobile 
troubles.  This  list  was  given  by  C.  G.  Anderson  as  a  part  of  an 
address  delivered  by  him  before  the  Gas  Engine  class  at  the 
Kansas  State  Agricultural  College. 


168  FARM  MOTORS 

^  S  fl  **  OS         m 

'So  -"'"si"    ^  ^ 

Is  £i|g!i        o  ,  II 


a?  55  53 


°3^«  a  ^  .S  "2 


s  §   "  2       ;^>^                     -s  t»HH^«  o        "  .a  §& 

P^  2     ct  S  ^1°  g-^  2^o  S        I  -cSS  .  ^  ^Sa 

S  o|2§  I  «1f  ^§3i  1^1  I     I  |||i  I  .         ^J 

Q  SS"a  o  -^^-g  -^-f^  °o|^  Is     gg  §|.^.S  11  §    .2|gg^g 


PJ^  s-^sf!  s'^^t:>  ^      -^S^i  ^2   I. 


o  oj-r 


s-a>^-s^    s^Tl  |Si°  il^il        ^si  ^fe      |1^l    °s   I1|2|3 

§e|5f.§1   p-ss  -s^^l    p^^af        ^s  ||      ^&a.   |-   ^-^g^is 


O   2  ■+:>'" 


03  ^ 


a  I    ai  i?s    |i       111     |g|  I  si  o3| 


i  it  ssK.  a 

jO-53  12;  a  gaiTS^oc&a  ^fl 


5  a  « 

•S  O?  '3      ^ 

a^s  a.2s 


os 


o 

2=fl 
-?2 


TRACTION  ENGINES  AND  AUTOMOBILES      169 


o  ,<» 

"o  fl     CO 


2  S 


Q  OCS73S  SSgfls  -^  -mS 


2^ 


H         g    S  -^   S  ;^  -^  -S  ^   °    I 

2  .2  I  a  o     I  S  g  g  I  g 

oQ   ;3  ^  -a    n      .^ ^ ,       ^   a  -^    o 


^      2.21^3     -gSgglg      &|      £      .g  I 


h?'       , ,  >  .2  >-    C3    o  tj         (3 


r.  §  o^.ag  o;"S.^.£f'^d.2fl§)§°'S'"S3 


m 

>-i 

o 

S 

o 

o 

•43 

H 

(N   "3 

P 
1 

O   ^ 

to 

W 

eS 

h:i 

PQ 

< 

^J 

&H 

M  "S 

'S  -« 

03    to 

l^ 

•^    >> 

02    fl 

O"  ^C3mp^03  j^> 


CO     g 
^    0 


a  o 


170 


FARM  MOTORS 


Gasoline  Motor  Cycles. — This  chapter  would  be  incomplete 
without  some  mention  of  the  gasoline  motor  cycle,  which  is 
becoming  very  popular  even  in  the  rural  districts.  It  is  light 
and  can  be  driven  over  roads  impossible  to  pass  by  four-wheel 
machines. 

The  power  plant  of  the  motor  cycle  is  either  a  single-cylinder, 
a  twin-cylinder  or  a  four-cylinder  engine.  The  power  plant 
of  the  latest  motor  cycles  varies  in  capacity  from  4  to  10  h.p. 


Fig.  177. 


The  single-  and  twin-cylinder  machines  are  most  popular  on  ac- 
count of  lower  first  cost.  The  motors  differ  from  the  automo- 
bile motors  in  that  the  cylinders  are  always  air  cooled.  The 
inlet  valve  is  either  mechanically  or  automatically  operated. 

Float  feed  carbureters  of  the  automobile  type  and  high  tension 
^magnetos  are  employed. 

Motor  cycles  are  started  by  the  use  of  the  petal,  by  a  hand 
crank,  or  by  a  foot  lever.  Belt  and  chain  drives  are  used,  the 
belt  drives  being  more  common.  Some  of  the  newer  models  are 
provided  with  a  clutch  to  free  the  engine  from  propelling  mechan- 
ism, and  operate  on  two  speeds.  The  general  appearance  of  a  four- 
cylinder  motor  cycle  is  illustrated  in  Figs.  177.  All  motor  cycles 
operate  on  the  four-stroke  cycle,  but  lately  a  two-stroke  cycle 
valveless  motor  appeared  on  the  market. 


CHAPTER  VIII 

WATER  MOTORS 

A  water  motor  converts  the  energy  possessed  by  moving  or 
falling  water  into  useful  work. 

Determining  the  Power  of  Streams. — Before  explaining  the 
various  commercial  types  of  water  motors,  the  method  of  deter- 
mining the  power  available  in  any  water  stream  will  be  given. 

The  power  available  in  any  stream  depends  on  the  head  of 
water  and  on  the  quantity  of  water  which  can  be  utilized  in  a 
water  motor.  » 

The  term  head  is  applied  to  the  fall  of  water  available.  The 
head  can  be  determined  most  readily  by  running  an  engineer's 
level  from  a  point  at  the  upper  line  of  water  flow  to  a  point  at 
the  lower  line  of  flow.  The  vertical  distance  between  the  two 
points  gives  the  head  of  the  stream. 

One  method  of  determining  the  quantity  of  water  available 
for  utilization  in  a  motor,  is  to  find  the  cross-sectional  area  of 
the  stream,  and  to  multiply  this  by  the  velocity  of  the  stream. 
The  cross-sectional  area  of  a  stream  can  be  obtained  by  multiply- 
ing the  average  depth  of  the  stream  by  its  width.  To  find  the 
velocity,  several  floats  are  dropped  in  the  water  at  a  place  where 
the  depth  and  width  is  uniform  for  some  distance,  noting  the 
number  of  seconds  it  takes  for  the  floats  to  pass  a  certain  dis- 
tance. Since  the  velocity  of  a  stream  is  greatest  at  the, center 
and  is  least  at  the  bottom  and  sides,  the  velocity  as  obtained 
by  floats  should  be  multiplied  by  0.80  to  obtain  the  average 
velocity. 

As  an  illustration,  the  average  width  of  a  stream  is  10  ft., 
its  average  depth  is  4  ft.  and  the  velocity  of  the  water,  as  obtained 
by  floats,  is  30  ft.  per  minute.  If  the  head  of  the  water  is  10  ft. 
calculate  the  power  which  could  be  obtained  from  a  water 
motor,  assuming  the  various  losses  in  the  motor  as  30  per  cent, 
and  the  average  stream  velocity  0.80  of  the  float  velocity. 

The  area  of  the  cross-section  of  the  stream  =  10  X4  =  40  ft. 

The  quantity  of  water  available  per  second  is  equal  to 

171 


172 


FARM  MOTORS 


40X1/2X0.80  =  16  cu.  ft. 

As  the  weight  of  a  cubic  foot  of  water  is  62.4  lb.  at  ordinary 
temperatures,  the  weight  of  water  delivered  to  the  motor  per 
second  is, 

62.4X16  =  998.4  lb. 

The  work  done  by  the  water  is, 

998.4X10  =  9984  ft.-lb. 

One  horse-power  is  equal  to  33,000  ft.-lb.  per  minute,  or  550  ft.- 
lb.  per  second;  allowing  30  per  cent,  for  friction,  the  power 
available  is, 

9984(1-0.30) 
550 


=  12.7  h.p. 


Fig.  178. 

Another  method  for  finding  the  quantity  of  water  available 
in  a  stream,  called  the  weir  dam  method  is  illustrated  in  Figs.  178. 
A  notch  is  cut  in  a  thick  board  placed  at  some  point  in  the 
stream. 


WATER  MOTORS  173 

The  length  of  the  notch  should  be  less  than  two-thirds  the 
width  of  the  board.  The  bottom  of  the  notch  is  called  the  creit 
of  the  weir,  and  the  depth  of  the  water  at  that  place  should 
be  more  than  three  times  the  depth  of  the  water  flowing  over 
the  weir.  The  crest  of  the  weir  should  be  perfectly  level  and 
should  be  beveled  on  the  down-stream  side.  The  edges  of  the 
notch  should  also  be  beveled  on  the  same  side.  In  the 
stream  back  of  the  weir,  and  at  a  distance  somewhat  greater 
than  the  length  of  the  notch,  a  stake  is  driven  level  with  the 
bottom  of  the  notch  or  crest  of  the  weir.  When  the  water  is 
flowing  over  the  weir,  measure  the  height  of  water  above  the 
top  of  the  stake.  If  this  height  in  feet  is  called  H  and  the' width 
of  the  notch  in  feet  B,  the  quantity  of  water  Q  flowing  through 
the  stream,  in  cubic  feet  per  second,  can  be  determined  by  the 
formula : 

Q  =  3.33BH\/H 

As  an  illustration,  if  the  width  of  the  notch  is  4  ft.  and  the 
depth  of  water  on  the  weir  is  12  in.  the  quantity  of  water  avail- 
able per  second  is: 

Q  =  3.33  X  4X^  Vy|=13.32  cu.  ft. 

Since  1  cu.  ft.  of  water  =  7.48  gallons,  the  quantity  of  water  de- 
livered in  gallons  is, 

13.32  X  7.48  =  99.6  gallons. 

Types  of  Water  Motors. — The  water  motors  mostly  used  at 
the  present  time  are  water  wheels,  which  are  made  to  revolve 
either  by  the  weight  of  water  falling  from  a  higher  to  a  lower  level, 
or  by  the  dynamic  pressure  which  is  produced  by  changes  in  the 
direction  and  velocity  of  flowing  water. 

Reciprocating  water  motors  are  used  to  a  limited  extent  for 
special  purposes.  Any  steam  engine  with  slight  modifications 
can  be  used  as  a  reciprocating  water  motor,  but  would  run  at 
slow  speed  on  account  of  the  incompressibility  of  water. 

Overshot,  Undershot  and  Breast  Wheels. — The  earlier  water 
motors  derived  their  power  from  the  weight  of  water  acting  on 
vanes  placed  around  the  rim  of  a  wheel. 


174 


FARM  MOTORS 


Of  these  the  overshot  wheel  receives  its  power  from  the  weight 
of  water  carried  by  buckets  on  the  circumference  of  a  wheel,  the 
water  entering  the  buckets  near  the  top  of  the  wheel  and  being 
discharged  near  the  bottom  (Fig.  179).     A  wheel  of  this  type  can 


Fig.  179. 

be  easily  constructed  by  inserting  between  two  wooden  discs  a 
number  of  buckets,  made  like  V-shaped  troughs  (Fig.  179),  and 
putting  a  wooden  or  metal  shaft  at  the  center  of  the  discs. 
Water  is  supplied  from  an  open  trough  near  the  top  of  the  wheel. 


y///////////////////////////////^/^ 


Fig.  180. 


Motors  of  this  character  can  be  built  to  operate  on  falls  as  low 
as  4  ft.  and  will  supply  from  3  to  50  h.p.,  depending  on  the  head 
of  the  fall  and  on  the  quantity  of  water  available. 


WATER  MOTORS 


175 


The  undershot  wheel  is  propelled  by  water  passing  beneath 
it  in  a  direction  nearly  horizontal,  which  impinges  on  vanes 
carried  by  the  wheel.  Such  wheels  have  been  used  to  some  ex- 
tent for  irrigation  work.  Some  of  the  undershot  wheels  have 
straight  flat  projections  for  vanes  (Fig.  180),  but  the  more  effi- 
cient wheels  are  built  with  curved  vanes.  Such  motors  are  suit- 
able for  very  low  falls,  provided  the  velocity  of  the  water  is  great. 

The  breast  wheel  (Fig.  181)  receives  water  at  or  near  the  level 
of  its  axis,  but  is  otherwise  quite  similar  in  its  action  to  the  over- 
shot wheel.  Breast  wheels  are  provided  with  either  radial 
vanes,  or  with  vanes  slightly  curved  backward  near  the 
circumference. 

All  these  wheels  are  very  bulky  for  the  power  developed,  as 
compared  with  the  more  modern  types  of  water  motors. 


Fig.  181. 


Impulse  Water  Motors. — Impulse  water  motors  are  provided 
with  buckets  or  cups  around  the  circumference  of  a  wheel,  which 
are  acted  upon  by  a  jet  of  water  issuing  from  a  nozzle. 

Among  impulse  water  motors,  the  Pelton  wheel  illustrated 
in  Fig.  182  is  used  to  a  considerable  extent  in  the  United 
States.  It  consists  of  a  series  of  cups  or  buckets  B  placed  at 
equal  intervals  around  the  circumference  of  an  iron  wheel. 
The  characteristic  feature  of  the  Pelton  motor  is  the  shape  of 
the  buckets.  These  are  made  in  the  form  of  two  half  cylinders 
with   closed  ends,  joined  together  at  the  center  by  a  straight 


176 


FARM  MOTORS 


thin  rib.  The  power  is  derived  from  the  pressure  of  a  head 
of  water  suppHed  by  a  pipe  which  discharges  upon  the  buckets  of 
the  wheel.     The  water  from  the  nozzle  N  striking  the  rib,  divides 


Fig.  182. 

into  two  streams,  one  going  into  each  half  cylinder  and  exerting 
a  pressure  on  the  curved  surfaces  of  the  buckets.  The  Pelton 
water  motor  is  usually  furnished  with  two  nozzle  tips  of  dif- 


FiG.  183. 

ferent  diameters.  By  changing  the  tip,  the  size  of  the  stream  on 
the  wheel  is  altered  and  a  great  variation  in  power  may  be 
obtained. 


WATER  MOTORS 


177 


Pelton  water  motors  can  be  secured  in  very  small  sizes  under- 
1  h.p.    and  up  to  several  hundred  horse-power.     The  efficiency 
of  this  type  of  motor  is  greatest  at  high  heads,  but  in  small  sizes 
it  will  be  found  as  efficient  as  most  water  motors,  even  for 
heads  as  low  as  15  ft. 

Another  type  of  water  motor  illustrated  in  Fig.  183  is  made  in 
sizes  less  than  1/2  h.p.  and  is  used  for  running  washing  machines, 


Fig.  184. — Water  motor  driving  an  ice  cream  freezer. 

sewing  machines,  grindstones,  fans,  small  feed  grinders,  and  for 
other  purposes  requiring  little  power. 

An  impulse  water  motor  can  be  operated  from  city  water  mains 
or  from  an  independent  stream. 

Some  of  the  applications  of  water  motors  are  illustrated  in 
Figs.  184  and  185. 

Water  Turbines. — A  water  turbine  is  a  water  motor  which 
is  made  up  of  a  number  of  stationary  and  movable  curved 
pipes.     It  consists  of  the  following  parts: 

12 


178 


FARM  MOTORS 


1.  A  gate  by  means  of  which  the  supply  of  water  to  the  tur- 
bine is  regulated. 

2.  A  guiding  element  consisting  of  stationary  blades,  the  func- 
tion of  which  is  to  dehver  the  water  to  the  revolving  element  in 
the  proper  direction  and  with  the  proper  velocity. 


Fig.  185. — Water  motor  driving  a  sewing  machine. 

3.  A  revolving  element  or  rotor,  consisting  of  vanes  or  buckets 
which  are  arranged  in  any  one  of  several  different  ways  around  the 
axis  of  the  motor. 

Water  turbines  are  divided  into  radial  outward  flow,  radial 
inward  flow  and  mixed  flow  types. 

In  the  radial  outward-flow  turbine  the  water  is  received  at  the 
center  and  is  delivered  at  the  periphery  of  the  revolving  buckets. 


WATER  MOTORS 


179 


In  the  radial  inward-flow  types  the  stationary  or  guiding  elenaent 
is  located  on  the  outside  of  the  revolving  part,  and  the  water 
flows  from  the  rim  toward  the  center. 

The  advantages  of  turbines  over  impulse  wheels  lie  in  the  fact 
that  a  turbine  can  be  utilized  for  very  low  falls.  The  turbines 
illustrated  in  Figs.  186  to  188  can  be  used  on  falls  as  low  as  4  ft. 


Fig.  186. 


and  will  develop  about  3  h.p.  with  a  water  supply  of  about  500 
cu.  ft.  per  minute. 

The  general  appearance  of  a  water-power  installation  with 
vertical  turbines  is  shown  in  Fig.  187. 

The  appHcation  of  turbines  for  the  driving  of  centrifugal  pumps 
is  illustrated  in  Fig.  188. 

The  Hydraulic  Ram. — The  hydraulic  ram  combines  in  one 
simple  machine  a  motor  and  a  pump.  It  is  probably  the  simplest 
and  most  economical  method  for  supplying  water  for  the  farm- 
house, the  feed  yard,  barn  and  the  dairy  where  conditions  are 


180 


FARM  MOTORS 


favorable.     It  can  also  be  used  to  advantage,  under  certain  con- 
ditions, for  irrigating  small  tracts  of  land. 

Hydraulic  rams  are  low  in  first  cost  and  inexpensive  to  operate. 
They  are  not  economical  in  water,  as  a  large  amount  of  water 
must  be  wasted  in  comparison  with  the  work  done. 


Fig.  187. — Morgan-Smith  turbines. 

The  working  of  the  hydraulic  ram  depends  on  the  fact  that  the 
momentum  of  a  large  quantity  of  water  falling  through  a  small 
height  is  capable  of  lifting  a  small  quantity  of  water  to  a  consid- 
erable elevation. 


WATER  MOTORS 


181 


A  section  of  a  hydraulic  ram  is  shown  in  Fig.  189.     It  consists 
of  a  working  valve  V,  a  check  valve  D,  an  air  chamber  C,  a  drive 


Fig.  188. 


lU' 


Fig.  189. 


pipe  A  which  supplies  water  to  the  ram,  and  a  delivery  pipe  B 
which  carries  the  water  to  the  place  where  it  is  utilized. 


182 


FARM  MOTORS 


The  ram  is  located  at  a  place  where  a  fall  of  2  to  10  ft.  can  be 
obtained.  The  water  from  the  source  enters  the  drive  pipe  (A 
in  Fig.  189)  and  flows  through  the  working  valve  V.  The  veloc- 
ity of  water  in  this  pipe  increases  and  when  a  'certain  velocity  is 
reached,  the  pressure  of  the  water  on  the  under  side  of  valve  V 
is  sufficient  to  close  it  abruptly.  The  flow  of  the  water  through 
the  working  valve  being  interrupted,  the  pressure  increases  and 
causes  the  check  valve  D  under  the  air  chamber  C  to  open,  and 


Fig.  190. 


a  part  of  the  water  is  forced  in  the  air  chamber  compressing  the 
air  in  that  chamber.  The  velocity  of  the  water  in  the  drive  pipe 
having  been  arrested,  a  recoil  or  ramming  takes  place,  the  pres- 
sure in  the  space  below  air  chamber  check  valve  D  is  reduced, 
thus  closing  the  check  valve  D  and  allowing  the  working  valve  to 
open.  The  operations  are  then  repeated.  The  delivery  pipe 
to  the  storage  tank  at  the  higher  elevation  is  attached  to  the  air 
chamber  below  the  water  level.  The  air  under  compression  in 
the  air  chamber  forces  the  water  in  a  steady  stream  through  the 
delivery  pipe  B  and  to  the  storage  tank.     Hydraulic  rams  are 


WATER  MOTORS  183 

also  provided  with  a  sniffing  valve,  not  shown  in  the  figure,  the^ 
function  of  which  is  to  replace  any  air  in  the  air  chamber,  lost  by- 
being  dissolved  in  the  water. 

A  hydrauUc  ram  is  illustrated  in  Fig.  190.     A  is  the  drive  pipe, 
B  the  discharge  pipe,  C  the  air  chamber  and  V  the  working  valve. 


CHAPTER  IX 

WINDMILLS 

Types  of  Windmills. — The  windmill  is  a  motor  which  converts 
the  kinetic  energy  of  the  wind  into  useful  work. 

Some  of  the  earlier  windmills  were  constructed  with  sails 
which  consisted  of  wooden  frames,  the  broad  sides  of  which  were 
covered  with  cloth.  These  sails  were  turned  by  the  wind  in 
horizontal  or  vertical  planes.  One  of  these  mills,  the  Dutch 
type,  is  illustrated  in  Fig.  191.  As  the  direction  of  the  wind 
changed,  the  entire  wheel-house,  including  shafting  and  machinery, 

was  rotated  on  a  pivot  so  as  to  bring 
I  the  wheel   to  face  up  to   the   wind. 

This  limited  the  size  of  the  mill.  In 
the  latter  types  of  the  Dutch  mill, 
only  the  upper  part  of  the  wheel- 
house  was  rotated.  These  mills  were 
governed  by  varying  the  extent  of  the 
sail  surface  exposed  to  the  wind  by 
hand,  while  the  wheel  was  at  rest. 
The  Dutch  types  of  wooden  mills  are 
Fig.  191.— Dutch  windmill,     powerful,    but    bulky  and  expensive. 

They  are  but  little  used  in  this  country 
at  the  present  time. 

The  American  mill  is  made  up  of  a  great  number  of  narrow 
blades  or  fans.  This  means  a  mill  of  smaller  weight  and  less 
bulk  than  the  Dutch  mill  of  the  same  power. 

Windmills  may  be  classified  as  pumping  and  power  windmills. 
The  pumping  windmill  gives  a  reciprocating  motion  to  a  vertical 
rod  suitable  for  operating  a  pump,  while  the  power  windmill 
gives  rotary  motion  to  a  shaft  through  a  train  of  gears. 

The  wheel  and  rudder  of  American  windmills  are  constructed 
either  of  wood  or  of  steel.  The  best  steel  windmills  are  galvan- 
ized for  protection  from  rust. 

184 


WINDMILLS 


185 


Windmills  are  designated  by  the  diameter  of  the  wind  wheeL 
Thus  the  so-called  15-ft.  mill  has  a  wheel  15  ft.  in  diameter. 

American  windmills  are  built  either  as  direct  stroke  or  as  back- 
geared.  In  the  case  of  the  direct  stroke  windmill  the  main  shaft 
carries  a  crank  which  is  attached  to  the  pump  rod  by  a  connect- 
ing rod,  commonly  called  the  pitman,  there  being  no  speed  re- 
ducing gears.  In  this  type,  the  pump  makes  one  complete 
stroke  for  each  revolution  of  the  wind 

wheel.     Geared  mills  are  back-geared,  v. 

so  that  the  pump  makes  one  stroke  for 
every  three  or  five  revolutions  of  the 
wind  wheel.  The  back-geared  mill  will 
develop  more  power  than  the  direct- 
connected  mill  for  a  wind  wheel  of  the 
same  diameter. 

Principal  Parts  of  a  Windmill. — The 
principal  parts  of  a  windmill  are : 

1.  A  wind  wheel  which  receives  the 
kinetic  energy  of  the  wind.  This  wheel 
is  carried  upon  the  main  shaft. 

2.  A  rudder  or  vane  which  steers  the 
wheel  against  the  wind. 

3.  A  governor,  which  regulates  the 
speed  of  the  wind  wheel. 

4.  Gearing. 

5.  A  brake  which  holds  the  wheel  stationary  when  out  of  the 
wind. 

6.  Main  casting  which  supports  governor,  gearing  and  brake. 
This  with  the  parts  which  it  supports  is  called  the  mill  head. 

7.  A  tower  which  is  a  support  for  the  mill.  The  tower  should 
be  tall  enough  to  raise  the  wheel  sufficiently  high  above  all  ob- 
structions, such  as  trees,  houses,  etc.,  so  that  the  wheel  will  re- 
ceive a  steady  breeze. 

The  Wind  Wheel.— The  wmd  wheel  (Fig.  193)  is  that  part  of 
the  mill  which  derives  the  energy  from  the  wind. 

The  hub  of  the  wheel  either  consists  of  two  separate  wheel  spi- 
ders (Fig.  192)  keyed  to  the  main  shaft,  or  it  is  constructed  as  a 
solid  casting  with  the  wheel  spiders  at  either  end. 

The  arms  or  spokes  of  the  wheel  (S  in  Fig.  193)  are  attached 


Fig.  192. — Hub  of  aermotor 
wind  wheel. 


186 


FARM  MOTORS 


to  the  wheel  spiders  (P)  and  extend  outward  to  the  rim  R.  The 
spokes  are  usually  of  rectangular  or  circular  cross-section,  but 
some  manufacturers  use  steel  angles. 


Fig.  193. 


Fig.  194. — Fans  of  aermotor  windmill. 


The  rims  are  placed  one  near  the  inner  ends  of  the  fans  F, 
and  the  other  either  a  little  beyond  the  center  or  near  the  outer 
ends  of  the  fans.  The  rims  are  made  either  of  strap  steel  or  of 
angle  steel. 


WINDMILLS  187 

The  fans  (Figs.  193  and  194)  are  so  curved  that  the  wind -on- 
leaving  one  fan  will  not  strike  upon  the  back  of  the  next.  The 
spacing  of  the  fans  is  such  that  the  wind  passes  through  freely 
and  all  parts  of  the  wheel  must  be  so  designed  as  to  offer  the  least 
resistance  to  the  wind.  The  fans  are  fastened  to  the  rims  by 
brackets  and  the  various  sections  of  fans  and  rims  are  riveted 
together. 

Figure  195  shows  a  Samson  wheel  with  strap  steel  spokes  and 
hollow  hub. 


Fig.  195. — Samson  wheel. 

The  general  construction  of  a  wooden  wind  wheel  is  similar 
to  that  of  the  steel  wheel,  except  that  the  spokes,  rims  and  fans 
are  of  wood.  The  rims  are  made  either  straight  from  spoke  to 
spoke  or  are  bent  in  a  manner  similar  to  that  of  steel  mills.  A 
section  of  a  wooden  wind  wheel  is  illustrated  in  Fig.  196.  The 
wooden  wind  wheel  is  made  up  of  six  or  more  sections,  each  sec- 
tion consisting  of  15  or  more  slats. 

The  Rudder  or  Vane. — Most  windmills  are  provided  with 
some  form  of  rudder  or  vane  for  keeping  the  wheel  in  the  direc- 
tion of  the  wind.  In  some  windmills  no  rudder  is  employed,  and 
the  pressure  of  the  wheel  on  the  wind  wheel  is  relied  upon  to 


188 


FARM  MOTORS 


bring  the  wheel  in  the  right  direction.  Windmills  without 
rudders  are  provided  with  folding  wheel  fans  and  have  a  weighted 
ball  which  performs  the  function  of  a  rudder  and  opens  the 
wheel  when  the  wind  is  greater  than  the  load.  Then  some  of  the 
larger  windmills  without  rudders  are  provided  with  a  small  side 


Fig.  196. 

wheel  which  is  set  perpendicular  to  the  wind  wheel,  and  turns 
the  wind  wheel  into  the  proper  direction  by  means  of  gearing. 

The  rudder  is  built  either  of  steel  (Fig.  197  )  or  of  wood  (Fig. 
198). 


ERMOTOR 

CHICAGO       ^' 


1 


Fig.  197.— Steel  rudder. 


It  is  often  desired  to  throw  the  wind  wheel  out  of  action. 
This  in  the  case  of  the  folding  wheel  is  accomplished  from  the 
ground  level  by  a  wire  or  rod  "which  extends  up  through  the  tower 
and  connects  with  a  system  of  levers  which  tip  the  sections  of 
the  wheel.     The  solid  wheel  is  thrown  out  of  action  either  by 


WINDMILLS 


189 


pulling  it  around  parallel  with  the  vane,  so  that  its  edge  faces^ 
the  wind,  or  by  pulling  the  vanes  parallel  to  the  wind. 

The  Governor. — The  function  of  a  governor  is  to  regulate  the 
speed  of  the  wind  wheel. 


Fig.  198. 


In  some  windmills  the  governor  consists  of  a  coiled  spring, 
one  end  of  which  engages  with  the  rudder  and  the  other  with  the 
mill  head.  When  the  wind  pressure  becomes  too  great,  the 
wheel  will  swing  so  as  to  expose  less  surface  to  the  wind. 


Fig.  199. 

To  assist  in  governing,  some  mills  are  provided  with  a  side 
vane. 

In  the  case  of  folding  wheel  mills  the  angle  of  the  fans  is 
changed,  by  a  system  of  weights  and  levers,  according  to  the 
intensity  of  the  wind. 


190 


FARM  MOTORS 


Most  windmills  are  provided  with  a  ''pull-out  reel/^  which 
consists  of  a  ratchet  and  windlass  for  throwing  the  wind  wheel 
out  of  action.  When  the  ratchet  is  released  the  wind  wheel  is 
thrown  into  correct  position  by  the  rudder  and  governor.  Some 
windmills  use  a  lever  instead  of  a  ratchet  and  windlass  for  the 
same  purpose. 

Windmill  Gearing. — The  gearing  of  a  direct-stroke  windmill 
is  illustrated  in  Fig.  199.  A  is  the  inner  wheel  spider  which  is 
attached  to  the  main  shaft  B.  A  crank  on  the  main  shaft  is 
connected  with  the  rocker  arm  R  by  means  of  a  pitman.  The 
pump  rod  is  fastened  directly  to  the  outer  end  of  the  rocker  arm. 

A  chain  is  attached  to  the  two 
pulleys  O  and  P  and  connects 
with  the  pull-out  reel  explained  in 
the  last  section. 

One  simple  form  of  a  back- 
geared  mill  mechanism  is  given  in 
Fig.  200.  E  represents  the  hub 
of  the  wind  wheel.  The  pinion 
P  is  carried  on  the  main  shaft  and 
meshes  with  a  large  gear  A  on  a 
counter-shaft.  The  center  of  the 
gear  A  is  placed  to  one  side  of 
the  upper  end  of  the  connecting 
rod  or  pitman  B,  so  that  it  re- 
quires more  than  half  of  a  revo- 
lution to  raise  the  pump  rod  and 
less  than  half  of  a  revolution  to 
lower  it.  Thus  a  quick  return 
motion  is  obtained,  the  pump  rod 
descending  more  rapidly  than  it 
rises.  This  is  advantageous  in 
that  little  power  is  required  on  the  down  stroke,  there  being  no 
water  raised  and  the  weight  of  the  plunger,  pump  pole  and 
pump  rod  being  sufficient  to  produce  that  stroke.  The  slow 
motion  on  the  up  stroke  enables  the  mechanism  to  carry  the 
load  with  the  least  strain.  In  this  mechanism  D  is  a  hinge  for 
attaching  the  rudder  or  vane. 

The  difference  in  construction  between  the  gearing  for  pump- 


FiG.  200. 


WINDMILLS 


191 


Fig.  201. 


192  FARM  MOTORS 

ing  and  power  windmills  is  in  the  addition  of  a  bevel  gear  B 
(Fig.  201)  which  meshes  with  another  bevel  gear  on  the  power 
shaft. 

All  windmills  should  be  provided  with  some  form  of  buffer  to 
protect  the  rudder  and  other  parts  from  sudden  shocks  when  the 
windmill  is  thrown  out  of  gear.  The  buffer  is  usually  constructed 
in  the  form  of  a  helical  steel  spring  placed  upon  the  rudder  rail 
near  the  hinge. 

Windmill  Brake. — Nearly  all  windmills  are  provided  with  an 
automatic  brake,  which  holds  the  wheel  stationary  when  out  of 
the  wind.  The  brake  is  a  flexible  steel  band  which  encircles 
about  three-fourths  of  the  flange  on  the  hub  of  the  wind  wheel 
and  holds  it  stationary  when  out  of  gear.  The  brake  is  applied 
by  a  lever  as  soon  as  the  windmill  is  turned  out  of  gear. 

Towers. — Windmill  towers  are  constructed  either  of  wood  or 
of  steel. 

There  are  a  great  many  different  kinds  of  wooden  towers  as 
they  are  often  ''home-made."  Four  4-in.  by  4-in.  or  6-in.  by 
6-in.  timbers,  depending  on  the  size  of  the  tower,  are  most  com- 
monly employed  for  the  corner  posts.  They  are  spread  about 
8  or  10  ft.  at  the  bottom  and  are  brought  together  at  the 
top  and  fastened  to  a  cast-iron  cap,  usually  provided  by  the 
manufacturer.  A  platform  2  or  3  ft.  square  should  be  provided 
directly  below  the  wind  wheel  for  the  purpose  of  facilitating 
oiling,  inspection  and  repairing.  The  tower  ends  of  the  corner 
posts  are  bolted  to  anchor  posts  which  are  set  about  6  ft.  in  the 
ground  with  cross  pieces  bolted  to  the  lower  end  to  form  a  better 
foundation. 

Steel  windmill  towers  are  built  with  either  three  or  four 
posts  and  should  always  be  galvanized  and  not  painted.  A  tower 
supported  on  four  posts  (Fig.  202)  is  protected  from  a  wind  in 
either  direction.  The  three-post  tower  (Fig.  203)  is  somewhat 
cheaper  than  the  four-post  tower,  and  has  the  additional  ad- 
vantages for  localities  where  the  ground  is  soft,  in  that  the  tower 
always  stands  firm  and  rigid,  and  is  not  affected  by  unequal 
settling  of  anchor  posts.  A  three-post  tower  when  properly 
braced  is  also  stiffer  and  stronger  than  a  four-post  tower. 

The  corner  posts  of  a  steel  tower  are  usually  of  angle  steel, 
but  some  are  of  gas  pipe.     The  cross  girts  are  of  angle  steel  and 


WINDMILLS 


193 


Fig.  202.— Four-post  tower. 


1^ 


194 


FARM  MOTORS 


Fig.  203. — Three-post  tower. 


WINDMILLS  195 

the  braces  may  be  of  angle  steel,  rods,  or  wire  cable.  The  anchor 
posts  are  about  6  ft.  long  and  of  the  same  material  as  the 
corner  posts,  with  anchor  plates  attached  at  the  lower  end. 

The  method  of  fastening  the  corner  posts  of  three-  and  four- 
post  towers  is  shown  in  Fig.  204.  The  posts  are  beveled,  notched 
and  are  held  together  by  clamps  and  bolts. 

The  tower  in  Fig.  205  has  the  lower  braces  of  angle  steel  and 
the  other  braces  of  rods.  Twisted  wire  cable  braces  are  shown 
in  Fig.  206. 

Method  of  Erecting  Windmills. — A  windmill  is  erected  either 
by  building  it  up  in  position  piece  by  piece,  or  it  is  assembled 
on  the  ground  and  then  raised  into  position.  The  method  of 
raising  a  windmill  from  the  ground  is  illustrated  in  Fig.  207. 


Fig.  204. — Method  of  fastening  corner  posts  of  S^post  and  4-post  aermotor 

towers. 


After  the  holes  for  the  anchor  posts  are  dug,  the  anchor  posts 
are  placed  loosely  in  them.  In  raising  towers  over  30  ft.  in 
height,  the  lower  portion  should  be  reinforced  by  placing  timbers 
in  the  tower  (Fig.  207).  A  beam  of  wood  is  then  placed  across 
the  lower  ends  of  the  legs,  and  stakes  are  driven  at  each  end,  in 
order  to  prevent  the  tower  from  sliding  when  it  is  being  raised. 
A  strong  rope  is  attached  to  the  tower  near  the  platform  and  to 
a  block  and  tackle  a  little  beyond  the  lower  end  of  the  tower. 
Another  block  is  made  fast  to  some  stakes  driven  at  a  distance 
of  one  and  one-half  times  the  length  of  the  tower  from  the  lower 
end  of   the  tower.     Shear  poles  about  one-half  the  length  of 


196 


FARM  MOTORS 


Fig.  205. — Tower  of  aermotor  windmill. 


Fig.  206. — Twisted  wire  braces. 


WINDMILLS 


197 


the  tower  are  then  placed  under  the  rope  near  the  lower-f^4 
of  the  tower.  Stakes  are  driven  at  each  side  of  the  upper 
end  of  the  tower  and  the  tower  is  pulled  into   position   by  a 


Fig.  207. — Method  of  raising  windmill  from  the  ground. 


traction  engine,  team,   or  windlass.     Several  men  can  usually 
raise  a  small  tower  by  pulling  directly  on  the  tackle  rope. 

After  the  tower  is  in  position  it  should  be  leveled  with  a 
plumb  bob,  before  the  pump  rod  is  put  in  place.  All  braces 
must  be  evenly  tightened. 


198 


FARM  MOTORS 


The  anchor  posts  are  then  bolted  to  the  corner  posts  and  the 
holes  filled  in.  Loose  stones  are  often  placed  below  and  above 
the  anchor  plate.  For  best  results  a  concrete  base  should  be 
used.  When  using  loose  stones,  it  is  desirable  that  the  anchor 
plates  should  rest  on  cap  stones. 

Care  of  Windmills. — A  windmill  requires  some  care  if  long 
and  good  service  is  expected. 

When  first  erected  it  should  be  carefully  examined  every  few 
days  for  loose  bolts  and  bearings. 

All  bearings  should  be  kept  well  lubricated  and  brasses  tight. 
If  anchor  posts  work  loose  they  should  be  reset.  It  is  always 
well  to  shut  down  a  windmill  during  a  heavy  storm. 


Fig.  208. 


Windmills  may  be  lubricated  by  means  of  oil  cups,  the  oil 
being  held  in  place  by  waste.  With  the  ordinary  oil  cups  a 
windmill  would  have  to  be  lubricated  every  two  or  three  days 
if  it  is  running  steady.  To  reduce  the  necessity  of  frequent 
lubrication,  some  form  of  self-feed  oil  cup  as  illustrated  in  Fig. 
208  is  used.  This  consists  of  a  large  oil  cup  A  with  a  tube  B 
extending  nearly  to  the  top  of  the  oil  cup.  A  twisted  wire  wick 
C  passes  from  the  bottom  of  the  oil  cup  into  the  tube.  The  oil 
from  the  cup  follows  the  wicking  into  the  tube  and  lubricates 
the  bearing  E  which  is  at  the  bottom  of  the  tube.  D  is  a  lid  for 
the  oil  cup. 

Power  of  Windmills. — The  power  delivered   by  a  windmill 


WINDMILLS  199 

depends  on  the  velocity  of  the  wind,  on  the  size  and  construetien 
of  the  wheel,  on  the  amount  of  power  lost  in  friction  and  on  the 
density  of  the  air. 

It  has  been  found  that  an  average  wind  velocity  of  6  miles  per 
hour  is  required  to  drive  a  windmill.  The  average  velocity  of 
the  wind  in  the  United  States  varies  from  4.2  to  16  miles  per  hour. 
The  velocity  in  most  localities  is  great  enough  to  operate  a  mill 
about  eight  hours  per  day. 

The  power  developed  by  a  windmill  with  winds  of  average 
intensity  will  vary  from  1/8  h.p.  for  a  6-ft.  wind  wheel  to  about 
1  h.p.  for  a  16-ft.  wind  wheel.  With  strong  winds  and  with 
large  wheels,  windmills  will  develop  as  much  as  4  h.p. 

The  angle  and  spacing  of  the  wind  wheel  fans  affect  the  power 
delivered  by  a  windmill.  Then  the  quality  and  condition  of  the 
gearing  and  bearings  determine  the  actual  power  available  for 
utilization  either  at  the  pump  or  power  shaft. 

The  density  of  the  air  affects  the  pressure  of  the  wind  on  the 
wind  wheel.  Thus  the  higher  the  altitude  the  lighter  is  the  air 
and  the  less  power  is  developed  with  a  wind  of  a  certain  velocity. 

Uses  of  Windmills. — The  main  use  of  windmills  is  for  pumping 
water  for  domestic  use  and  for  stock.  When  used  in  pumping 
water  for  irrigation,  a  storage  tank  of  large  capacity  should  be 
provided,  sufficient  for  several  days  use  in  case  of  calm  weather. 

For  watering  stock  on  small  farms  and  for  domestic  use  on  the 
farm,  the  windmill  is  the  cheapest  and  best  form  of  motor.  It 
requires  but  little  attention.  One-half  hour  per  week  devoted  to 
oiling  and  inspection  will  keep  the  mill  in  good  condition. 

A  windmill  cannot  be  used  for  heavy  work  on  the  farm,  but 
can  drive  small  feed  grinders,  grindstones,  corn  shellers,  feed 
cutters,  wood  saws,  churns  or  any  other  machine  requiring  little 
power. 

In  general  the  windmill  is  suitable  for  work  requiring  but  little 
power,  which  will  admit  of  suspension  during  calm  weather. 


CHAPTER  X 
ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES 

Before  considering  the  various  types  of  electric  motors  and  their 
applications,  the  fundamentals  of  electricity  and  of  dynamo 
electric  machinery  will  be  taken  up. 

Action  of  Electricity. — The  action  of  electricity  in  a  dynamo  is 
analogous  to  that  of  water  pumped  from  a  lower  to  a  higher  level. 
The  function  of  a  pump  in  forcing  water  through  pipes  is  well 
known.  The  pump  exerts  a  pressure  on  the  water.  If  the  pres- 
sure exerted  by  the  pump  is  doubled,  the  quantity  of  water  han- 
dled by  the  pump  will  also  be  doubled,  if  the  friction  of  the  water 
through  the  pipe  remains  the  same.  It  is  also  well  known  that 
the  resistance  offered  to  the  flow  of  water  through  pipes  increases 
with  the  length  of  the  pipe.  Also  by  increasing  the  size  of  the 
pipe  the  resistance  is  decreased. 

The  dynamo  in  the  electric  power  plant  performs  a  function 
similar  to  the  pump.  It  generates  electrical  pressure  in  order  to 
send  electricity  through  the  wires  which  correspond  to  pipes. 
The  resistance  offered  by  the  wire  to  the  flow  of  electricity  is 
analogous  to  that  offered  by  the  water  pipe  to  the  flow  of  water. 
The  quantity  of  electricity  delivered  to  the  circuit,  which  may 
consist  of  motors,  lamps  or  other  appliances  using  electricity, 
corresponds  to  the  amount  of  water  delivered  by  the  pump  to  an 
overhead  tank  or  pipe  from  which  water  motors  or  other  appli- 
ances requiring  water  under  pressure  can  be  operated. 

Units  of  Electricity. — The  pound  is  the  unit  of  water  pressure, 
while  the  unit  of  electricity  is  the  volt.  The  amount  of  water 
flowing  through  a  pipe  is  measured  in  gallons  per  minute,  the 
quantity  of  electricity  flowing  through  a  wire  in  amperes.  The 
resistance  which  a  wire  offers  to  the  flow  of  electricity  is  measured 
in  ohms. 

The  unit  of  electrical  power  is  the  watt,  a  watt  being  the  prod- 
uct of  a  volt  and  ampere.     This  is  evident  from  the  water  anal- 

200 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES    201 

ogy.  The  power  available  in  a  certain  weight  of  water  depends 
on  the  head,  or  distance  the  water  is  allowed  to  fall.  Similarly 
the  power  available  at  the  terminals  of  a  dynamo  is  the  product 
of  the  quantity  of  electricity  in  amperes  and  the  electrical  pres- 
sure head  in  volts. 

As  an  illustration,  the  power  available  at  the  terminals  of  a 
dynamo  delivering  60  amperes  at  110  volts  is. 

Power  in  watts  =  60  X 1 10  =  6600 

Dynamos  are  usually  rated  in  kilowatts  (kw.),  a  kilowatt  being 
1000  watts.  Electric  motors  are  rated  in  electrical  horse-power, 
an  electrical  horse-power  being  equal  to  746  watts.     The  relation 

between  the  kilowatt  and  the  electrical  horse-power  is -^j^  =11/3. 

Thus  an  electric  motor  operating  on  a  220-volt  circuit  and 
requiring  30  amperes  has  delivered  to  it, 

220X30     o  or.    1     .  •     IV. 

— ^^^ —  =  8 .  85  electrical  horse-power. 

If  the  efficiency  of  the  motor  is  80  per  cent.,  the  available  power 
at  the  motor  shaft  is  8.85X0.80  =  7.08  brake  horse-power. 

Ohm's  Law. — The  law  expressing  the  relation  between  the 
volt,  the  ampere  and  the  ohm  is  of  great  value  in  electrical 
calculations.  It  is  called  Ohm's  law  and  is  expressed  by  the 
statement  that 

^-  ,  .  Pressure  in  Volts 

The  current  m  amperes  =  ^5 — r-r ; — ^r 

^  Kesistance  m  Ohms. 

Expressing  the  current  by  the  symbol  I,  the  volt  by  E  and  the 
resistance  by  E, 

1=^ 
^     R 

As  an  illustration,  an  ordinary  16  candle-power  carbon  lamp 
operating  on  a  110-volt  circuit  offers  a  resistance  of  220  ohms. 
How  much  current  will  be  required  to  operate  the  lamp  ? 

Applying  Ohm's  law, — 

^     E     110  Volts       1 

^  =  R  =  220Ohm^  =  2^"^P^"^^- 


202 


FARM  MOTORS 


The  power  required  to  operate  the  lamp  is 

110X2=55  watts. 

Considering  no  losses  in  the  engine,  dynamo  and  lines,  the  num- 
ber of  16  candle-power  carbon  lamps  which  can  be  operated  by 
a  dynamo  driven  from  1  h.-p.  engine  is: 

746 

-^  =  13 .  56  lamps. 

Due  to  line  losses  and  to  losses  in  the  generator,  it  is  customary 
to  figure  about  ten  16  candle-power  carbon  filament  lamps  per 
engine  horse-power. 

Table  7  gives  the  current  consumption  of  carbon  filament 
lamps  of  various  candle-powers. 


TABLE  7.— CURRENT     CONSUMED     BY     CARBON     FILAMENT 
INCANDESCENT    LAMPS    OF    VARIOUS    CANDLE-POWERS 

Voltage 

8  c.p. 

10  c.p. 

16  c.p. 

20  c.p. 

24  c.p. 

32  c.p. 

50  c.p. 

52 
104 
110 
220 

0.55 
0.28 
0.26 
0.15 

0.69 
0.35 
0.33 
0.18 

1.11 
0.55 
0.52 
0.29 

1.38 
0.69 
0.65 
0.36- 

1.66 
0.83 
0.78 
0.44 

2.22 
1.11 
1.05 
0.58 

3.46 
1.73 
1.64 
0.91 

Wires  for  Conductors  of  Electricity. — The  resistance  which 
a  wire  offers  to  the  flow  of  electricity  depends  on  its  cross-section 
and  on  the  material  from  which  it  is  made.  Silver  when  pure 
is  considered  to  be  the  best  conductor.  Copper  is  very  nearly 
as  good  a  conductor  as  silver,  and,  being  much  cheaper,  it  is 
used  in  nearly  all  cases  for  the  distribution  of  electricity. 

Copper  wire  is  sometimes  used  bare,  but  in  most  cases  it  is 
covered  with  a  material  called  insulation,  to  prevent  the  transfer 
of  electricity  to  surrounding  substances.  The  insulation  used 
on  wire  is  either  rubber  or  some  weather-proof  substance. 

Copper  wires  are  designated  either  by  the  Brown  and  Sharpe 
wire  gage  (B.  &  S.  gage)  or  by  their  cross-section  in  circular 
mills.  A  circular  mill  is  a  circle  1/1000  in.  in  diameter.  The 
designation  of  wire  by  the  B.  &  S.  gage  is  more  common  for  small 
wires.  This  gage  is  constructed  so  that  the  numbers  decrease 
as  the  size  of  the  wire  increases.  Thus  a  No.  10  B.  &  S.  wire  is 
smaller  than  a  No.  9  and  larger  than  a  No.  11. 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  203 

The  current-carrying  capacities  in  amperes  of  various  siz£S 
of  rubber-covered  and  weather-proof  wire  is  given  in  Table  8. 


TABLE  8 


Size  of  copper  wire 

Current-caxrying 

Capacity  in 

rubber-covered 
wire 

amperes,  weather- 
proof wire 

B.  &  S.  gage 

Circ.  mills 

18 

1,624 

3 

5 

16 

2,583 

6 

8 

14 

4,107 

12 

16 

12 

6,530 

17 

23 

10 

10,380 

24 

32 

8 

16,510 

33 

46 

6 

26,250 

46 

65 

5 

33,100 

54 

77 

4 

41,740 

65 

92 

3 

52,630 

76 

110 

2 

66,370 

90 

131 

1 

83,690 

107 

156 

0 

105,500 

127 

185 

00 

133,100 

150 

220 

000 

167,800 

177 

262 

0000 

211,600 

210 

312 

The  sizes  of  wire  in  the  tables  are  given  in  terms  of  the  B.  &  S. 
gage  as  well  as  in  circular  mills. 

Electrical  Batteries. — Batteries  are  used  mainly  in  places 
where  the  current  requirement  is  small,  as  in  connection  with 
the  ignition  system  of  internal  combustion  engines,  also  for 
operating  telephones,  telegraphs,  electric  bells,  etc. 

Batteries  can  be  called  chemical  generators  of  electricity,  and 
are  of  two  types.  One  type,  called  the  primary  battery,  generates 
electrical  current  by  means  of  direct  chemical  action  between 
certain  substances.  Another  type  is  called  a  secondary  battery 
or  storage  battery,  requires  charging  with  electricity  from  some 
outside  electric  source  before  it  will  generate  electrical  energy. 
The  outside  current  acting  on  the  substances  within  the  battery 
changes  their  chemical  properties  to  such  an  extent  that  the 
battery  is  able  to  deliver  current  when  connected  to  a  circuit. 
After  storage  batteries  furnish  current  to  a  circuit  for  a  certain 
length  of  time,  their  active  materials  become  nearly  exhausted 
and  they  must  be  recharged  with  electricity  before  thay  can  be 


204 


FARM  MOTORS 


used  again.  Here  lies  the  difference  between  the  storage 
battery  and  the  ordinary  primary  battery.  The  active  materials 
in  the  primary  battery  when  once  exhausted  cannot  be  brought 
back  to  generate  electricity,  and  must  be  renewed. 

The  term  battery  is  applied  to  two  or  more  cells,  whether 
primary  or  storage  types,  which  are  connected  together  to  in- 
crease the  total  amount  of  electrical  energy  delivered  to  a 
circuit. 

Primary  Batteries. — A  primary  cell  consists  essentially  of  a 
vessel  containing  some  acid  called  the  electrolyte  in  which  are 
immersed  two  solid  conductors  of  electricity,  called  electrodes, 
one  of  which  is  more  easily  attacked  by  the  acid  than  the  other. 

A  simple  cell  consists  of  a  weak  solu- 
tion of  sulphuric  acid,  as  an  electro- 
lyte, a  plate  of  zinc,  which  is  easily 
decomposed  by  the  sulphuric  acid, 
and  a  plate  of  some  other  solid  like 
copper  or  carbon  which  resists  the 
action  of  sulphuric  acid.  If  the 
plates  of  zinc  and  copper  are  put 
side  by  side  in  a  vessel  containing 
sulphuric  acid,  and  the  circuit  is 
completed  by  joining  the  two 
plates  by  a  wire,  chemical  action 
will  be  set  up  within  the  vessel  or 
cell.  The  zinc  will  dissolve  in  the 
acid,  forming  zinc  sulphate,  hy- 
drogen will  be  given  up  by  the  sul- 
phuric acid  in  streams  of  bubbles 
which  will  settle  on  the  copper 
plate,  and  a  current  of  electricity 
will  be  generated.  The  bubbles 
of  hydrogen  liberated  from  the 
electrolyte  do  not  combine  with  the  copper  plate,  but  form  a 
gaseous  non-conducting  film  over  the  metaUic  surface  which 
increases  the  resistance  of  the  cell  to  the  flow  of  electric  cur- 
rent. The  formation  of  the  bubbles  of  hydrogen  on  the  cop- 
per plate,  called  polarization,  causes  a  rapid  falling  off  in  the 
power.     It  is  possible  to  decrease  or  even  eliminate  polariza- 


FiG.  209. 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  205 

tion.     One  good  method  is  to   construct  the  cell  with  some 
strong  oxidizmg  agent.     The  oxidizing  agent  gives  up  its  oxygen, 


.//FAMOUS  X 

vJATTERTi 


rMoRE  LIFE  y 


Fig.  210. 


which  combines  with  the  particles  of 
hydrogen,  forming  water  and  decreas- 
ing polarization.  Cells  using  this 
method  of  decreasing  polarization 
usually  employ  carbon  plates,  as 
most  of  the  oxidizing  materials  at- 
tack copper  plates.  The  Leclanche 
cell  shown  in  Fig.  209  is  an  example 
of  this  type  of  cell. 

The  dry  cell,  which  is  used  exten- 
sively at  the  present  time  on  account 
of  its  portability,  is  a  modification  of 
the  Leclanche  cell.  It  has  zinc  for 
the  positive  electrode,  carbon  for  the 
negative  electrode,  sal-ammoniac  and 
zinc  chloride  as  the  electrolyte  for  de- 
composing the  zinc,  and  some  oxidiz- 
ing agent  like  manganese  dioxide  to 
eliminate  polarization.  As  usually 
constructed  the  dry  cell  consists  of  a 
zinc   cylinder  which   is  the  positive 

electrode  and  acts  at  the  same  time  as  a  container  for  the  other 
materials  of  the  cell.     The  zinc  cylinder  is  provided  with  a  lin- 


Fig.  211. 


206  FARM  MOTORS 

ing  composed  of  plaster  of  Paris,  flour,  blotting-paper,  or  some 
other  absorbent  materials  saturated  with  salammoniac  and  zinc 
chloride.  At  the  center  of  the  cell  is  a  carbon  rod,  and  this  is 
surrounded  by  a  paste  consisting  of  manganese  dioxide  and 
chloride  of  zinc.  The  top  of  the  cell  is  covered  with  a  layer  of 
hard  pitch.  A  small  hole  through  the  pitch  permits  the  escape 
of  any  gases  which  may  be  formed  within  the  cell.  The  outside 
of  the  cell  is  usually  insulated  with  paper.  Several  forms  of 
dry  cells  are  illustrated  in  Fig.  210.  The  solution  in  the  dry 
cell  evaporates  slowly,  so  that  a  battery  of  dry  cells  will  become 
worthless  after  a  certain  time  even  if  it  is  not  used.  Generally  a 
dry  cell  in  good  condition  will  have  a  current  strength  of  15  to 
25  amperes  and  should  show  a  pressure  of  1  1/4  to  1  1/2  volts. 
A  binding  post  is  attached  to  the  carbon  and  another  one  to  the 
edge  of  the  zinc  cylinder. 

The  various  Lalande  wet  cells  are  very  good  for  gas-engine 
ignition.  One  form,  the  Edison  Lalande,  is  illustrated  in  Fig. 
211.  One  electrode  in  this  cell  is  of  zinc  and  the  other  of  copper 
oxide.  The  electrolyte  consists  of  caustic  potash.  The  oxy- 
gen of  the  copper  oxide  prevents  polarization.  A  film  of  heavy 
paraffin  oil  is  put  on  top  of  the  electrolyte,  so  as  to  prevent  the 
absorption  of  carbon  dioxide  from  the  air  by  the  caustic  potash. 

Storage  Batteries. — The  storage  cell  consists  of  two  plates  or 
electrodes  placed  in  an  electrolyte,  but  as  was  pointed  out  in  an 
earUer  part  of  this  chapter,  this  type  of  cell  will  give  out  no 
current  to  the  external  circuit  until  it  is  charged  with  electricity. 
The  storage  cell  does  not  store  electricity,  but  energy  in  the  form 
of  chemical  work.  The  electric  current  produces  chemical 
changes  in  the  battery  and  these  changes  produce  a  current  in 
the  opposite  direction  when  the  circuit  is  closed. 

In  storage  batteries  both  the  positive  and  negative  electrodes 
of  a  cell  are  of  lead  perforated  plates.  The  perforations  are  filled 
with  certain  lead  compounds  (Pb304  and  PbO),  which  react  with 
the  electrolyte  of  dilute  sulphuric  acid,  forming  lead  peroxide  on 
the  positive  plate  and  a  spongy  metallic  lead  on  the  negative 
plate. 

The  storage  cell  is  composed  of  an  odd  number  of  positive 
plates  and  of  an  even  number  of  negative  plates,  so  that  each  side 
of  each  positive  plate  faces  a  negative  plate.     The  plates  are 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  207 

insulated  from  each  other  and  from  the  bottom  and  are  placed^ 
in  a  glass  vessel  if  the  battery  is  to  be  used  for  stationary  purposes, 
and  in  a  vessel  of  hard  rubber  if  the  battery  is  for  portable  use. 
Various  forms  of  storage  batteries  are  illustrated  in  Fig.  212. 

A  storage  battery  can  be  charged  from  any  direct-current 
circuit,  provided  the  voltage  of  the  charging  circuit  is  greater 
than  that  of  the  storage  battery  when  fully  charged.  Before  a 
storage  battery  is  connected  to  the  charging  circuit  its  pol- 
arity should  be  carefully  determined,  and  the  positive  and 
negative  terminals  of  the  battery  connected  to  the  positive  and 
negative  terminals  of  the  source  respectively.     One  good  method 


Fig.  212. 

of  determining  the  polarity  of  the  wires  from  the  storage  battery 
or  source  is  to  immerse  them  in  a  glass  of  salt  water.  Bubbles 
of  gas  will  form  more  rapidly  on  the  surface  of  the  negative  wire. 
Another  test  is  that  the  negative  wire  will  turn  blue  litmus  paper 
red.  Should  the  positive  wire  of  the  battery  be  connected  to  the 
negative  wire  of  the  source,  the  effect  would  be  a  discharge  of  the 
battery,  and  this  being  assisted  by  the  incoming  current,  a  re- 
versal of  action  would  take  place,  which  is  very  injurious  to  the 
battery.  It  is  not  well  to  charge  a  battery  at  too  rapid  a  rate,  as 
this  will  raise  its  temperature  and  will  cause  buckling  of  the  bat- 
tery plates.  It  is  also  well  to  charge  batteries  at  regular  inter- 
vals. A  storage  battery  when  fully  charged  will  show  2.2  to  2.5 
volts  on  open  circuit  and  about  2.15  volts  when  the  circuit  is 
closed.  A  storage  battery  should  never  be  allowed  to  run  down 
to  a  voltage  lower  than  1.8. 


208 


FARM  MOTORS 


Storage  batteries  are  rated  by  their  ampere-hour  capacity, 
this  rating  being  based  on  the  time  required  for  the  storage  battery 
to  discharge.  Most  manufacturers  of  storage  batteries  specify 
the  rate  of  discharge.  If  the  rate  of  discharge  is  greater  than  the 
specified  amount,  the  capacity  of  the  battery  is  reduced.  A 
battery  having  a  capacity  of  800  ampere  hours,  means  that  the 
battery  is  capable  of  furnishing  100  amperes  for  8  hours.  If  the 
battery  is  connected  to  a  circuit  requiring  200  amperes,  the  ca- 
pacity will  be  reduced.  In  connection  with  this  it  should  be  under- 
stood that  a  single  storage  battery  cell  is  only  capable  of  furnish- 
ing a  pressure  of  about  2  volts.  If  a  storage  battery  is  to  supply 
110  volts,  about  sixty  cells  will  be  required. 

The  positive  and  negative  plates  of  a  storage  battery  can  be 
distinguished  by  their  color.     The  positive  plates  when  fully 

charged  should  have  a  dark  chocolate 
color,  and  the  negative  plates  more 
of  a  metallic  lead  color. 

For  successful  operation  and  long 
life,  storage  batteries  should  be  tested 
frequently  with  a  pocket  voltmeter 
for  voltage  and  with  a  hydrometer  for 
the  specific  gravity  of  the  electrolyte. 
A  battery  hydrometer  for  obtaining 
the  specific  gravity  is  illustrated  in 
Fig.  213.  The  specific  gravity  of  the 
electrolyte  should  vary  from  1.17  to 
1.22  when  the  battery  is  in  good  con- 
dition. If  too  low,  add  stronger  sul- 
phuric acid  until  the  correct  specific 
gravity  is  obtained. 
For  gas-engine  ignition  the  storage  battery  is  preferable  to  the 
primary  dry  or  wet  battery  on  account  of  its  greater  capacity 
and  more  uniform  voltage.  It  is,  however,  more  expensive  and 
can  only  be  used  in  places  where  direct  current  is  available  for 
recharging  purposes. 

Storage  batteries  are  used  to  a  considerable  extent,  as  will 
be  explained  later,  for  farm  lighting  to  shorten  the  running 
hours  of  the  engine  and  dynamo,  and  also  in  connection  with 
the   axle   system   of   train   lighting.     In   large   electric   power 


Fig.  213. 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  209 

plants,  the  storage  battery  finds  application  during  the  hours 
of  heavy  load. 

Methods  of  Connecting  Batteries. — The  various  methods  of 
connecting  batteries  are  illustrated  in  Fig.  214  to  216. 


ABC 

Fig.  214. 


In  the  series  battery  connection  (Fig.  214)  the  positive  (+) 
of  one  cell  is  connected  to  the  negative  (  — )  of  the  other  cell. 
The  voltage  of  the  battery  is  equal  to  the  sum  of  the  voltage  of 
the  cells  A,  B  and  C,  while  the  current  is  equal  to  that  of  one 
cell  only.  If  three  storage  cells,  each  having  a  pressure  of  2.1 
volts  are  connected  in  series,  the  pressure  of  the  battery  is  6.3 
volts. 

4-  Terminal 

—  rermfnaf 
Fig.  215. 

The  multiple  battery  connection  method  is  illustrated  in 
Fig.  215.  In  this  case  the  positive  terminals  are  connected,  as 
are  also  all  the  negative  terminals  of  the  battery.  If  the  external 
resistance  is  low,  the  current  of  the  battery  is  proportional  to 
the  number  of  cells,  while  the  pressure  in  volts  is  equal  to  that 
of  one  cell  only. 


Fig.  216. 

■ 
Another  method  shown  in  Fig.  216  and  called  the  multiple- 
series  method  of  connecting  batteries  consists  of  connecting  the 
battery  in  two  sets,  the  cells  of  each  set  being  connected  in 
series  and  the  two  sets  are  connected  in  multiple.     The  effect 

14 


210  FARM  MOTORS 

of  this  method  of  connecting  cells  is  that  the  total  pressure  of 
the  system  is  equal  to  that  of  three  cells  and  the  current  is  equal 
to  that  of  two  cells. 

The  Electric  Djniamo. — The  electric  dynamo  or  generator 
consists  essentially  of  an  armature  composed  of  coils  of  wire 
wound  around  an  iron  core,  and  one  or  more  magnets.  Either 
the  armature  or  the  magnets  must  be  given  motion  by  some 
form  of  motor  with  relation  to  the  other  before  the  djoiamo  can 
generate  a  current  of  electricity. 

The  magnet  may  be  a  permanent  magnet  or  an  electromagnet. 
A  permanent  magnet  is  made  of  hard-tempered  steel  which  after 
having  been  brought  under  the  influence  of  some  magnetizing 
apparatus,  will  retain  a  certain  amount  of  magnetism.  Perma- 
nent magnets  are  expensive  to  make  in  large  sizes  and  do 
not  hold  their  magnetism  for  any  length  of  time.  They  are 
employed  only  in  the  construction  of  small  electric  dynamos, 
called  magnetos,  which  are  used  mainly  in  connection  with 
electric  ignition  systems  for  gas  engines,  and  for  signaling 
work. 

Dynamos  which  generate  electric  current  for  commercial 
purposes  employ  electromagnets.  An  electromagnet  consists  of 
a  piece  of  iron  which  has  wound  around  it  many  turns  of  insulated 
copper  wire.  If  a  current  of  electricity  is  passed  through  the 
insulated  copper  wire,  the  iron  becomes  immediately  magnetized, 
and  remains  magnetized  as  long  as  the  current  is  passing  through 
the  wire.  There  is  practically  no  limit  to  the  strength  of  an  elec- 
tromagnet, as  this  depends  only  on  the  number  of  turns  of 
copper  wire  and  on  the  current  passing  through  the  wire,  or  on  the 
ampere  turns. 

Action  of  the  Dynamo. — The  action  of  a  dynamo  depends 
on  the  fact  that  when  a  wire  or  other  conductor  of  electricity 
is  moved  between  the  poles  of  a  magnet,  electrical  pressure 
is  induced  in  the  conductor.  In  the  simple  dynamo,  an  armature 
consisting  of  only  one  coil  of  wire  is  rotated  between  the  north 
and  south  poles  of  a  magnet.  The  ends  of  the  coil  are  connected 
to  two  insulated  rings  mounted  on  a  shaft  which  gives  rotary 
motion  to  the  coil.  If  two  brushes  are  allowed  to  bear  on  the 
two  rings  and  are  connected  to  a  measuring  instrument,  it  will 
be  noticed  that  the  current  will  flow  in  one  direction  during  half 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  211 

of  a  revolution  and  in  the  other  direction  during  the  next  half  ofa 
revolution.  If  the  readings  of  the  instrument  are  recorded 
graphically  a  curve  like  Fig.  217  will  be  obtained.  In  this  curve 
the  horizontal  distances  represent  the  angles  turned,  while  in  the 
vertical  distances  are  recorded  values  of  electrical  pressure  in 


Fig.  217. 


volts  which  cause  a  corresponding  flow  of  electric  current  at  the 
various  angular  positions.  It  will  be  noticed  that  the  current 
starts  at  zero,  and  increases  to  a  maximum  during  one-quarter 
turn.  At  the  half  turn  it  is  zero  again.  After  half  of  a  revolu- 
tion the  direction  of  the  current  re- 
verses, attains  a  negative  maximum  at 
three-quarters  of  a  turn  and  then  is 
again  diminished  to  zero. 

Direct  and  Alternating  Currents. — 
The  action  of  the  simple  dynamo, 
explained  in  the  last  section,  produces 
an  alternating  current,  which  varies 
from  a  maximum  to  a  minimum,  first 
in  one  direction  and  then  in  the  other. 
In  the  actual  dynamo  there  are  many 
conductors  in  the  armature  and  sev- 
eral sets  of  poles,  so  that  as  the  arm- 
ature revolves,  the  current  reverses 
its  direction  many  times  a  second. 
For  long-distance  electric  transmission 
this  type  of  electric  current  is  usually 
used,  as  alternating  currents   can  be 

generated  at  very  high  voltage,  and  these  voltages  can  be  in- 
creased or  decreased  at  pleasure  by  means  of  simple  instruments 
called  transformers.     There  are,  however,  certain  uses  to  which 


Fig.  218. 


212  FARM  MOTORS 

the  alternating  form  of  electric  current  cannot  be  put.  One 
case  was  mentioned  in  connection  with  the  charging  of  storage 
batteries,  where  a  direct  current  must  be  used,  the  chemical 
action  as  is  necessary  in  a  storage  battery  being  an  impossibility 
with  an  alternating  current. 

Direct  current  is  generated  in  a  dynamo  by 
the  addition  of  a  commutator  shown  in  Fig.  218, 
which  consists  of  a  set  of  segments  insulated 
from  each  other  and  from  the  armature  shaft, 
and  which  rectify  the  current  by  shifting  the 
position  of  the  brushes  with  respect  to  the  arma- 
FiG.  219.  ture  coils.  The  principle  of  the  commutator  can 
be  seen  from  Fig.  219.  R  is  a  split  ring  to  the 
two  segments  of  which  are  fastened  the  two  ends  of  the  coil, 
explained  in  connection  with  the  working  of  the  simple  dynamo. 
The  two  brushes  BC  are  connected  to  two  wires  carrying  off  the 
current  to  the  external  circuit.  As  the  coil  of  the  simple  arma- 
ture gets  into  the  vertical  position  between  the  poles  of  the  mag- 
net each  brush  changes  from  the  segment  with  which  it  was  in 
contact  to  the  other,  so  that  the  effect  is  just  the  same  as  if  the 
brushes  were  interchanged,  and  the  current  generated  during 
the  second  half  of  the  revolution  flows  in  the  same  direction  round 
the  external  circuit  as  the  preceding  current  did.  The  current 
although  generated  in  the  reverse  direction  enters  the  external 
circuit  at  the  other  end,  and  the  result  is  a  unidirectional  current. 
This  is  changed  into  a  direct  current  by  the  employment  of  an 
armature  with  a  large  number  of  coils  and  a  commutator  of  many 
segments. 

Principal  Parts  of  Dynamos  and  Motors. — The  principal  parts 
of  all  dynamo — electric  machinery,  whether  they  be  generators 
of  electricity  or  motors  driven  by  electric  current,  are : 

1.  A  magnetic  field,  commonly  called  a  field,  whose  function 
it  is  to  furnish  magnetic  lines.  In  the  earHer  machines  this  con- 
sisted of  a  two-pole  magnet  but  the  modern  dynamos  and  mo- 
tors are  provided  with  four  or  more  poles.  The  reason  for  this  is 
that  a  more  compact  machine  can  be  produced.  A  dynamo  whose 
field  consists  of  a  two-pole  magnet  is  called  a  bi-polar,  while  one 
with  a  magnet  consisting  of  four  or  more  poles  is  called  a  multi- 
polar dynamo. 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  213 

2.  An  armature  which  is  made  up  of  insulated  windings  of 
copper  wire  on  an  iron  core.  The  function  of  the  armature  is  to 
cut  the  magnetic  Hnes  of  fprce  furnished  by  the  field.  In  all 
direct-current  machines  the  field  is  the  stationary  part  while  the 
armature  revolves.  In  alternating-current  machines,  the  field 
is  the  revolving  part  in  all  but  the  very  small  machines. 

3.  A  device  which  collects  or  delivers  current  to  the  armature, 
depending  on  whether  the  machine  is  a  generator  or  a  motor. 
In  the  case  of  alternating-current  dynamos  and  motors  this  is 
accomplished  by  brushes  pressing  on  collector  rings,  if  the  arma- 


FiG.  220. 


ture  is  the  revolving  element.  In  larger  alternating-current 
machines  where  the  armature  is  the  stationary  part,  the  current 
is  taken  away  from  or  delivered  to  the  windings  by  leads  entering 
the  frame  of  the  dynamo  or  motor.  When  dealing  with  direct- 
current  machines,  current  is  delivered  to  or  taken  away  from  the 
armature  by  brushes  pressing  on  a  commutator  whose  function, 
as  explained  in  the  earlier  part  of  this  chapter,  is  also  to  change 
the  alternating  current  into  direct  current. 

4.  A  shaft  passing  through  the  revolving  part,  which  is  con- 
nected to  the  engine  furnishing  power  in  the  case  of  the  dynamo 
and  to  the  machine  to  be  driven  in  the  case  of  the  electric  motor. 

5.  A  frame,  usually  made  of  cast  iron,  whose  function  it  is 


214 


FARM  MOTORS 


to  support  the  bearings  in  which  the  shaft  of  the  dynamo  or  motor 
revolves. 

The  various  parts  of    a  direct-current  generator   or  motor 


Fig.  221. 


Fig.  222. 


are  illustrated  in  Fig.  220.  The  field  and  armature  of  an 
alternating-current  generator  are  illustrated  in  Figs.  221  and 
222  respectively. 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  215 

Classification  of  Djmamos  and  Motors. — The  first  broad 
classification  is  into  direct  and  alternating-current  dynamos 
and  motors. 

Direct-current  dynamos  and  motors  are  divided  into  three 
classes  depending  on  the  type  of  field  winding  as  series  wound, 
shunt  wound,  and  compound  wound.  For  simplicity  these 
three  types  are  represented  as  bi-polar  machines  in  Figs.  223, 
224,  and  225. 

Series-wound  Dynamos. — In  the  series-wound  dynamo,  illus- 
trated by  Fig.  223,  one  end  of  the  field  winding  is  connected  to 
the  positive  brush  and  the  other  to  the  external  circuit.     The 


Fig.  223. 

action  of  the  series-wound  machines  depends  on  the  fact  that  the 
soft  iron  poles  retain  sufficient  mangetism  to  send  out  a  current 
to  the  external  circuit  when  the  armature  is  rotated.  The  entire 
current  passing  through  the  field,  the  electromagnet  of  the  field 
increases  in  strength  as  the  current  developed  by  the  generator 
becomes  greater.  Series-wound  dynamos  are  used  mainly  to 
supply  electricity  to  direct-current  arc  lamps. 

Series-wound  Motors. — The  series-wound  motor  has  a  winding 
similar  to  that  of  the  series- wound  dynamo.  In  fact  it  is 
impossible  to  tell  the  difference  between  any  direct-current 
motor  and  dynamo,  the  electrical  features  being  the  same.  A 
series-wound  dynamo  when  operated  as  a  motor  will  run  in  re- 
verse direction.     The  series-wound  motor  is  used  for  work  where 


216 


FARM  MOTORS 


hand  control  can  be  used  as  in  the  operation  of  hoists,  cranes, 
and  for  the  propulsion  of  electric  cars.  A  series-wound  motor  can 
be  started  at  full  load  and  should  never  be  used  where  there  is  a 
possibility  for  the  load  to  be  removed  suddenly.  A  series-wound 
motor  will  ''run  away,"  that  is  its  speed  will  increase  to  such  an 
extent  that  it  may  be  destroyed  by  centrifugal  force,  if  the  load 
is  removed.  For  this  reason  it  is  not  safe  to  use  belt  drives  with 
series-wound  motors.  A  series  motor  is  illustrated  in  Fig.  223. 
Shunt-wound  Djmamos. — The  principle  of  a  shunt-wound  dy- 
namo is  illustrated  in  Fig.  224.     The  field  winding  consists  of  a 


':  -f     ^^^^ 


Fig.  224. 

great  number  of  turns  of  very  fine  wire.  Both  ends  of  the  field 
winding  are  connected  to  the  brushes  of  the  dynamo.  Since  the 
field  winding  is  very  small  in  comparison  to  the  line  wire,  only  a 
small  part  of  the  current  flows  around  the  field  coils.  This  type 
of  dynamo  is  used  for  charging  storage  batteries.  A  shunt-wound 
dynamo  will  supply  constant  voltage  provided  the  load  does  not 
vary  much. 

Shunt-wound  Motors. — The  shunt-wound  motor  has  the  same 
type  of  winding  as  the  shunt-wound  dynamo.  Shunt-wound 
motors  are  used  for  all  kinds  of  work  where  fairly  constant  speed  is 
desired.  A  well-designed  shunt-wound  motor  will  not  vary  much 
in  speed  with  a  variable  load.  In  starting  a  shunt-wound  motor 
it  is  necessary  to  put  a  considerable  resistance  in  series  with  the 
field  of  the  motor.     This  is  due  to  the  fact  that  the  resistance  of 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  217 

the  armature  of  shunt-wound  motor  is  very  low.  If  a  voltage  Txf 
110  to  220  volts  is  allowed  to  pass  through  an  armature  of  low 
resistance,  an  enormous  current  would  flow  through  the  armature 
in  starting,  which  would  result  in  injury  to  the  armature  coils, 
and  also  to  the  commutator  by  excessive  sparking.  By  putting 
a  resistance  in  series  with  the  armature  the  current  which  is 
allowed  to  pass  through  it  is  decreased.  Then,  as  the  motor 
begins  to  speed  up,  the  armature  turning  between  poles  of  a 
magnet,  produces  a  dynamo  action  which  sends  an  electrical  pres- 
sure in  opposition  to  that  which  is  sent  in  from  the  mains.  This 
tends  to  reduce  the  current  passing  through  the  armature  to  a 


Fig.  225. 


safe  limit.  In  connection  with  this,  it  must  be  remembered,  that 
weakening  the  field  of  a  shunt-wound  motor,  reduces  the  above- 
mentioned  dynamo  action,  and  speeds  up  the  motor.  A  break 
in  the  field  connection  of  a  shunt-wound  motor,  while  it  is  in  opera- 
tion, may  result  in  considerable  damage  by  overspeeding. 

Compound -wound  D3niamos. — The  compound-wound  dynamo 
is  used  extensively  for  the  generation  of  current  for  all  purposes, 
including  that  for  light,  power  and  street-car  propulsion.  The 
voltage  of  this  type  of  machine  is  automatically  regulated  by  a 
combination  of  a  shunt  and  series  winding.  This  type  of  winding 
is  illustrated  in  Fig.  225.  A  large  portion  of  the  field  is  wound 
with  many  turns  of  fine  insulated  wire,  which  must  produce  a 
field  of  sufficient  .strength  to  generate  the  rated  voltage  of  the 


218  '        FARM  MOTORS 

dynamo  when  no  load  is  placed  on  it.  A  series  winding  of  several 
turns  of  heavy  wire  is  wound  over  the  shunt  winding.  This 
series  winding  adds  sufficient  strength  to  the  field  so  as  to  de- 
velop the  standard  voltage  at  the  maximum  load  of  the  dynamo. 
In  some  compound-wound  dynamos,  the  series  winding  is  ar- 
ranged to  increase  the  voltage  slightly  as  the  load  increases,  and 
to  compensate  for  loss  in  voltage  during  transmission. 

Compound-wound  Motors. — The  compound-wound  motor  has 
a  series  and  shunt  winding  like  the  compound-wound  dynamo. 
It  is  used  mainly  for  the  driving  of  machines  where  very  close 
speed  regulation  is  essential,  such  as  printing  presses,  machine 
tools,  and  looms. 

Various  T3rpes  of  Motors  Compared. — For  most  purposes, 
the  shunt-wound  motor  is  very  satisfactory,  and,  being  much 
cheaper  than  the  compound-wound  motor  it  is  used  for  the  driv- 
ing of  all  kinds  of  machinery,  which  can  be  started  at  no  load.  If 
motors  are  to  be  used  for  pumping  the  series-wound  or  compound- 
wound  motor  should  be  selected,  unless  a  clutch  can  be  inserted 
between  the  motor  and  pump. 


^ 

A 

;  6  6  6  6  6  6  : 

B 


Fig.  226. 


Distribution  of  Electric  Current. — Electricity  may  be  dis- 
tributed as  direct  or  as  alternating  current.  Direct  current 
is  usually  used  for  short-distance  distribution,  the  most  com- 
mon voltages  being  110  and  220  volts.  If  the  furthest  point 
of  the  distributing  system  is  a  mile  or  further  from  the  dy- 
namo it  is  well  to  use  alternating  currents  in  order  to  reduce  the 
cost  of  wire.  Alternating  currents  are  used  in  voltages  of  1100, 
2200,  4400,  6600,  and  higher. 

When  using  direct  currents  the  parallel  system  of  distribution 
is  most  common.  The  principle  of  this  system  is  illustrated  in 
Fig.  226.  The  feeders  A  and  B  lead  from  the  dynamo  D  to  the 
switchboard.  The  mains  EF  and  GH  connect  the  feeders  with 
the  branches  whieh  supply  current  for  lamps,  motors,  etc. 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  219 

In  another  system  of  direct-current  distribution,  the  series, 
shown  in  Fig.  227,  the  lamps  are  connected  in  series  with  the  dy- 
namo D.  This  system  is  very  seldom  used  at  the  present  time, 
and  then  only  for  supplying  current  to  direct-current  street  arc 
lamps. 

Electric  Meters. — The  four  most  important  quantities  which 
must  be  known  are :  current,  voltage  or  electrical  pressure,  resist- 


FiG.  227. 

ance  and  power.  Then  most  switchboards  are  also  provided 
with  ground  detectors  for  the  purpose  of  telling  when  the  circuit 
is  grounded. 

Electric  current  is  measured  by  an  instrument  called  an  amme- 
ter, and  illustrated  by  Fig.  228.     This  instrument  usually  con- 


FiG.  228. 


Fig.  229. 


sists  of  a  coil  of  wire  between  the  poles  of  a  permanent  magnet. 
The  current  to  be  measured  is  sent  through  the  coil,  this  produc- 
ing a  movement  of  the  coil  which  is  recorded  by  a  needle  on  a 
graduated  scale. 

A  voltmeter,  illustrated  in  Fig.  229  is  used  for  measuring  elec- 
tric pressure.     This  instrument  differs  from  the  ammeter  in  that 


220 


FARM  MOTORS 


a  resistance  is  placed  in  series  with  the  coil,  otherwise  the  volt- 
meter and  ammeter  for  the  measurement  of  direct  current  are 
aHke. 

For  the  measurement  of  voltage  and  current  of  batteries  a 
battery  meter  illustrated  in  Fig.  230  is  used. 

The  method  of  connecting  an  ammeter  M  and  a  voltmeter  V 
to  a  circuit  is  shown  in  Fig.  231.  AB  and  CD  are  the  two  wires 
of  the  circuit. 


Fig.  230. 


n 


—  [) 


Fig.  231. 


Resistance  can  be  measured  by  using  a  voltmeter  and  an 
ammeter  together.  The  ammeter  is  connected  in  series  with 
the  resistance,  while  the  voltmeter  is  connected  to  the  terminals. 
The  resistance  can  then  be  calculated  by  Ohm's  law,  explained 
in  the  beginning  of  this  chapter.  If  I  is  the  ammeter  reading 
and  E  is  the  voltmeter  reading  the  resistance  is: 

R  =  ? 


An  instrument  which  measures  the  electrical  power  of  a  circuit 
is  called  a  wattmeter.  Since  the  power  of  a  direct-current  cir- 
cuit is  the  product  of  the  current  flowing  through  the  circuit  by 
the  voltage  between  the  terminals,  the  power  can  be  obtained 
by  taking  the  product  of  the  voltmeter  and  ammeter  readings  of 
any  circuit.  In  alternating-current  circuits  this  product  of  the 
voltmeter  and  ammeter  readings  does  not  give  the  true  electric 
power  of  the  circuit  and  a  wattmeter  must  be  used.  Direct  and 
alternating  current  wattmeters  are  illustrated  in  Figs.  232 
and  233  respectively.- 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  221 


Fig.  232. 


Fig.  233. 


222 


FARM  MOTORS 


A  ground  detector  can  usually  be  made  by  connecting  two 
lamps  as  shown  in  Fig.  234.  The  two  lamps  LL'  are  connected 
to  the  two  terminals  and  the  junction  between  the  two  lamps  is 


+ 


L 

o 


L' 

o 


Fig.  234. 

grounded  to  a  water  pipe.  When  the  system  is  free  from  grounds 
both  lamps  will  burn  dim,  but  when  a  ground  occurs  on  either 
line  the  opposite  lamp  will  burn  bright. 


Fig.  235. 

Fuses  and  Circuit  Breakers. — The  function  of  fuses  and  of 
circuit  breakers  is  to  protect  electric  machines,  appliances  and 
wires  from  being  traversed  by  currents  above  their  safe  carrying 
capacities. 


Fig.  236. — Edison  plug  cut-out  and  fuse. 

Fuses  are  made  of  an  alloy  of  lead  and  zinc.     For  temporary 
connections  fuse  wire  is  used.     A  better  method  is  to  solder  the 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  223 

wire  to  copper  terminals  as  shown  in  Fig.  235.  The  Edison  plug 
cut-out  and  fuse,  illustrated  in  Fig.  236  is  very  convenient. 
Another  form,  the  enclosed  type  of  fuse,  is  shown  in  Fig.  237. 

Due  to  the  uncertainty  and  unreliability  of  fuses,  circuit 
breakers  are  employed  for  the  protection  of  lines  carrying  heavy 
currents. 


^ 


Fig.  237. 

Several  forms  of  circuit  breakers  are  illustrated  in  Fig.  238.  A 
circuit  breaker  is  a  switch  which  opens  automatically  where  the 
current  passing  through  it  is  greater  than  that  for  which  it  is 
set.     Circuit  breakers  are  made  to  open  either  one  or  both  sides 


Fig.  238. 


of  the  circuit  and  are  named  accordingly  single-pole  and  double- 
pole  circuit  breakers  respectively. 

Switches  and  Rheostats. — The  functions  of  a  switch  and  rheo- 
stat in  an  electrical  circuit  are  analogous  to  that  of  a  valve  in  a 
steam  or  water  line.  The  switch  opens  or  closes  the  circuit  while 
the  rheostat  regulates  the  strength  of  the  current  passing. 


224 

FARM  MOTORS 

«            « 

A 

^ 

m 

^ 

i^.. 

^ 

Fig.  239. 


Fig.  240. 


^-. 

^ 

if  ~".^ 

yi 

^^K 

^K-                   '^'^--                  W 

w 

'^^p*' 

^*«w""'^' 

Fig.  241. 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  225 

For  controlling  the  flow  of  small  currents  in  connection  wittr 
the  illumination  of  rooms,  some  form  of  snap  switch  or  push- 
button switch  is  employed.     These  switches  can  be  brought  to 
control  the  current  from  two,  three  or  four  different  places.     A 
special  form  of  push-button  or  snap  switch,  called  the  electrolier 


Fig.  242. 


Fig.  243. 


switch  can  be  used  for  turning  on  part  of  the  lamps  on  an  electric- 
light  chandelier.  Thus  in  the  case  of  a  4-light  chandelier,  this 
type  of  switch  can  be  wired  so  that  the  burning  of  one,  two, 
three  or  all  of  the  lamps  can  be  controlled  from  the  wall  of  the 
room.  Several  forms  of  snap  and  push-button  switches  are 
illustrated  in  Fig.  239. 

For  currents  above  25  amperes  a  knife  switch  should  be  em- 
ployed. This  type  of  switch  has  a  contact-making  piece  of  a 
shape  somewhat  like  a  knife.    A  single-pole  knife  switch  opens 


15 


226  FARM  MOTORS 

only  one  side  of  a  circuit,  a  double-pole  two  sides,  etc.  Double- 
throw  switches  are  used  when  one  of  two  circuits  has  to  be  con- 
trolled at  a  time.  Several  forms  of  knife  switches  are  illus- 
trated in  Fig.  240. 

A  rheostat  for  controlling  the  strength  of  electric  current  is 
illustrated  in  Fig.  241.  The  fundamental  parts  of  a  rheostat 
are :  coils  of  iron  wire  to  absorb  electric  current,  metallic  points 
connecting  the  various  coils  to  the  outside,  and  an  arm  which  is 
moved  over  the  various  points. 

Method  of  Connecting  Motors. — The  method  of  connecting 
a  shunt  motor  and  its  starting  box  to  the  circuit  is  illustrated 
in  Fig.  242.  A  and  B  are  the  two  leads  which  bring  the  cur- 
rent from  the  mains  (connected  to  a  dynamo)  through  the 
fuses  P.  R.  and  to  the  switch  S.  One  terminal  of  the  switch 
L  is  connected  to  the  field  F  and  to  the  armature  G  of  the 
motor.  The  other  terminal  K  leads  to  the  starting  box.  The 
handle  H  of  the  starting  box  is  connected  with  the  terminal 
E,  which  is  attached  to  the  armature  of  the  motor.  The  other 
terminal  D  of  the  starting  box  is  connected  with  the  field  of  the 
motor  F. 

When  the  motor  is  to  be  started,  the  switch  S  is  closed  and  the 
handle  H  is  on  the  contact  point  1.  The  handle  H  is  then 
moved  slowly  to  the  right.  When  the  handle  H  is  on  the  last 
contact  point,  it  is  held  in  position  by  the  magnet  M.  To  stop 
the  motor,  the  switch  S  is  opened.  The  magnet  M,  losing  its 
magnetism  allows  a  spring  to  bring  back  the  arm  H  to  the 
starting-point. 

The  Electric  Motor  on  the  Farm. — The  electric  motor  is  well 
suited  for  most  farm  work  which  is  accomplished  by  the  small 
stationary  gasoline  engine.  It  is  not  as  portable  in  any  but  the 
very  small  sizes,  but  possesses  other  advantages  for  certain 
uses.  A  small  electric  motor  requires  no  special  foundation  and 
may  be  placed  on  the  floor,  on  a  truck,  or  may  be  fastened  to 
the  wall  or  ceiling,  is  easily  started  and  requires  less  care  than 
the  gasoline  engine.  The  cleanliness  of  the  electric  motor  and 
the  absence  of  offensive  fumes  makes  it  more  desirable  for  use 
in  the  house,  the  dairy  and  the  barn. 

The  use  of  the  electric  motor  in  the  home  is  illustrated  in  Figs. 
243  to  248.     The  house  pump  driven  by  a  motor  of  J  h.p.  is 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  227 

shown  in  Fig.  243.  Another  electric  motor  of  tV  h.p.  drives-?tr 
washing  machine  illustrated  in  Fig.  244.  Still  a  smaller  motor 
is  shown  connected  to  a  sewing  machine  in  Fig.  245.  Other 
uses  to  which  the  electric  motor  can  be  put  in  the  farm  house- 
hold may  be  mentioned :  the  driving  of  fans  during  hot  weather 


Fig,  244. 


(Fig,  246),  of  vacuum  cleaners,  of  ice-cream  freezers,  of  cream 
separators  (Fig.  247),  churns,  of  milking  machines  and  of  grind- 
stones (Fig,  248).  An  electric  motor  can  also  be  used  for  the 
shelling  and  grinding  of  feed  and  for  the  many  operations  in 
the  farm  shop. 


228 


FARM  MOTORS 


For  out-door  use  and  for  the  heavier  farming  operations  the 
electric  motor  is  not  as  suitable  as  the  gasoline  engine. 

The  application  of  electric  motors  to  grain  elevators,  chop 
mills  and  flour  mills  are  illustrated  in  Figs.  249  to  251. 

The  Farm  Electric -light  Plant. — For  farms  of  the  average 
si^e,  which  do  not  have  the  advantages  of  cheap  power  from 


Fig.  245. 


a  nearby  transmission   system,    private  electric-lighting  plants 
driven  by  gasoline  engines  are  becoming  quite  common. 

When  an  electric-Hght  plant  is  to  supply  current  for  Hghting 
only,  the  complete  installation  including  the  wiring  of  an  average 
eight-room  house  and  barn  will  vary  from  $500  to  $750,     If  the 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  229 


Fig.  246. 


Fig.  247. 


230 


FARM  MOTORS 


Fig.  248. 


Fig,  249. 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  231 

plant  is  to  supply  current  for  motors  as  well  as  for  lights  the  first 
cost  will  be  from  $1200  up,  depending  on  the  size  of  motors  used. 
The  cost  of  operating  a  plant  for  lighting  only  will  usually  be 
about  $15  a  year.  The  cost  of  operating  plants  which  supply 
electricity  for  power  will  depend  on  the  size  of  motors  and  on  the 
amount  of  work  done. 

The  essential  parts  of  a  private  electric-light  plant  are: 

1.  A  gasoline  engine  and  a  dynamo. 


Fig.  250. 


2.  A  set  of  storage  batteries  for  storing  the  electricity  to  be 
used  when  wanted  and  which  supplies  a  steady  light  whether 
the  engine  is  running  or  not. 

3.  A  switchboard  with  an  ammeter,  voltmeter,  fuses  and 
switches  to  control  operation  of  the  dynamo  and  of  the  storage 
battery. 

4.  Wires  from  the  switchboard  to  the  house,  barn  and  other 
places  where  electricity  is  to  be  used. 


232 


FARM  MOTORS 


Fig.  251. 


P 

1 

1 

■ 

PvT'^V"'  ' 

'MMirjf''' 

-  '"^^ 

BmJHw  \^.. 

.^ 

',.;  * 

E^ 

"^WSm. 

J^ 

i 

m 

^- 

0         ,^ 

Sm 

Bf 'HT^sl^^^l^B  E^ 

^^.. 

.^ 

HlMfcH^H 

mfi^ 

^ 

1™ 

M-- 

1 

^^^^hPk? 

Fig.  252. 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  233 

5.  Wiring  of  the  house,  barn,  etc.  ~ 

In  Fig.  252  is  illustrated  a  farm  electric-light  plant,  which  was 
installed  in  the  engineering  laboratories  of  the  Kansas  State 
Agricultural  College  for  experimental  purposes. 

The  use  of  the  private  electric-light  plant  for  farms  of  average 
size  was  out  of  the  question  until  quite  recently  on  account  of  the 
great  cost  of  the  storage  battery.  With  the  ordinary  carbon  lamps 
operating  at  110  volts,  about  sixty  storage  cells  were  required  to 
maintain  the  correct  voltage  when  the  engine  was  not  running. 


Fig.  253. 


The  development  of  the  tungsten  lamp,  which  operates  satis- 
factory at  about  30  volts,  necessitates  the  use  of  a  battery  of  only 
seventeen  cells,  and  has  the  added  advantage  of  greater  safety  from 
short  circuits.  Then  the  tungsten  lamp  consumes  only  about 
one-third  of  the  electric  energy  required  by  the  carbon  lamp  of 
the  same  candle-power. 

Installation  of  Electric  Motors  and  Dynamos. — A  dry,  cool 
and  clean  place,  free  from  dust,  should  be  chosen  for  the  location 
of  an  electric  machine.     If  the  surrounding  air  is  warm,  the  tem- 


234  FARM  MOTORS 

peratures  of  the  various  parts  is  likely  to  rise  to  a  sufficient 
degree  as  to  endanger  armature,  or  field,  or  both. 

If  a  motor  has  to  be  located  in  a  dusty  place,  or  in  connection 
with  farming  operations  where  particles  of  feed  or  trash  may  lodge 
on  the  motor,  an  enclosed  type  like  the  one  shown  in  Fig.  253 
should  be  selected. 

In  locating  motors  or  dynamos  care  should  be  taken  to  provide 
easy  access  to  all  parts.  Also  sufficient  distance  must  be  allowed 
between  the  pulley  centers  of  the  driver  and  driven. 

A  substantial  foundation  of  timber,  brick  or  concrete  should 
be  provided  for  all  motors  and  dynamos  above  25  h.p.  Small 
machines  can  be  fastened  to  the  floor  and  require  no  special 
foundation. 

If  an  electric  machine  has  been  exposed  to  changes  of  climate, 
it  should  be  kept  in  a  warm  dry  place  for  several  days,  as  the 
insulation  always  absorbs  dampness  which  can  be  only  slowly 
dried  out. 

Small  machines  are  usually  shipped  complete  and  ready  to 
run.  Large  motors  and  dynamos  are  usually  shipped  in  boxes, 
''knocked  down,"  as  this  reduces  freight  charges. 

In  assembling  parts,  all  connections  and  parts  should  be  wiped 
perfectly  clean  and  free  from  grit.  The  bearing  sleeves  and  oil 
rings  should  be  placed  in  position  on  the  shaft  before  the  armature 
is  lowered  in  place. 

The  bearings  should  be  filled  with  a  good  grade  of  thin  lubri- 
cating oil,  care  being  taken  not  to  fill  the  oil  cellars  so  they  will 
overflow. 

In  clamping  the  brushes  in  place,  they  should  be  adjusted  so 
that  the  pressure  on  the  commutator  is  about  1  1/2  lb. 

The  brushes  are  fitted  to  the  commutator  by  passing  beneath 
them  No.  0  sandpaper,  the  rough  side  against  the  brush  and  the 
smooth  side  held  down  closely  against  the  surface  of  the  commu- 
tator. The  sandpaper  should  be  moved  in  the  direction  of  rota- 
tion of  the  armature,  and  on  drawing  it  back  for  the  next  cut,  the 
brush  should  be  raised  so  as  to  free  it  from  the  sandpaper.  It  is 
then  lowered  and  repeated  until  a  perfect  fit  is  obtained  between 
the  brush  and  commutator. 

Starting  and  Stopping  Motors. — Before  starting  a  machine 
for  the  first  time,  care  must  be  taken  that  all  set  screws  and  nuts 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  235 

are  tight  and  that  the  oiling  system  works  properly.  The  arnm- 
ture  is  then  turned  by  hand  to  see  that  it  is  free  and  does  not  rub 
or  bind  at  any  point.  The  wiring  should  be  carefully  gone  over 
and  all  terminals  screwed  down  tightly.  When  everything  is  in 
good  condition,  the  switch  is  closed,  but  before  doing  this  one 
must  make  certain  that  the  starting-box  handle  is  in  the  ''off" 
position.  After  the  switch  is  closed,  the  handle  on  the  rheo- 
stat is  moved,  gradually  cutting  out  the  resistance  as  the  motor 
speeds  up. 

It  is  well  to  run  a  new  motor  for  a  time  before  putting  on  the 
load. 

In  stopping  a  motor,  pull  the  switch  and  the  handle  of  the 
starting  rheostat  should  fly  back  to  the  ''off''  position. 

Starting  and  Stopping  Dynamos. — The  general  rules  regarding 
getting  an  electric  machine  ready  to  start  are  alike  for  the  dynamo 
and  motor.  When  the  dynamo  is  ready  to  be  started,  place  the 
driving  belt  on  the  pulley  of  the  armature  shaft  and  start  the 
engine  driving  the  dynamo,  bringing  the  machine  up  to  speed 
very  slowly. 

Dynamos  are  usually  tested  before  they  leave  the  factory. 
As  a  rule,  dynamos  will  retain  sufficient  magnetism  in  their 
fields  so  they  can  be  started.  Sometimes  a  dynamo  loses  its 
field  magnetism  on  the  way  from  the  factory  to  its  destination. 
The  fields  can  be  magnetized  by  current  from  a  battery  or  from 
another  dynamo. 

If  a  dynamo  is  supplying  incandescent  lamps,  the  main  switch 
should  not  be  closed  until  the  machine  is  developing  the  correct 
voltage. 

In  stopping  a  dynamo,  the  load  is  first  removed  and  the  engine 
driving  the  dynamo  is  then  stopped  in  the  usual  manner. 

Care  of  Motors  and  Dynamos. — It  is  very  important  to  keep 
electric  machines  clean  and  all  insulation  free  from  dust  and  gritty 
substances. 

The  commutator  should  be  kept  clean  and  allowed  to  assume 
a  glaze  while  running.  Oil  should  not  be  used  on  commutators, 
as  it  chars  under  the  brushes,  forming  a  film  between  commutator 
bars  which  may  cause  a  short  circuit. 

The  commutator  brushes  should  be  kept  in  good  shape.  They 
should  be  removed  frequently  for  inspection  and  cleaning,  and 


236  FARM  MOTORS 

if  necessary  should  be  filed.  To  remove  grease  or  dirt  the  brushes 
should  be  soaked  in  gasoline. 

If  the  brushes  are  not  properly  trimmed  or  are  in  poor  condi- 
tion the  commutator  will  present  a  bright  coppery  appearance 
and  will  be  found  rough  when  felt  by  hand.  If  in  very  poor 
condition,  the  commutator  may  have  to  be  turned  down. 

Sparking  at  commutators  will  usually  occur  if  brushes  are 
improperly  set,  commutator  is  rough,  machine  is  overloaded, 
short  circuited  or  grounded. 

Heating  of  armatures  may  be  caused  by  the  short  circuiting 
of  some  of  the  armature  coils  or  by  too  great  a  load.  A  short- 
circUited  armature  coil  can  be  usually  detected  by  its  high  tem- 
perature. If  a  greater  part  of  the  coils  are  short  circuited  the 
determination  becomes  more  difficult  and  sensitive  instruments 
have  to  be  used. 

A  hot  bearing  will  also  cause  the  heating  of  the  armature,  and 
this  can  be  usually  detected  and  remedied. 

PROBLEMS 

1.  How  much  current  would  an  ordinary  32  candle-power  carbon  filament 
lamp  consume  on  a  11 0-volt  circuit? 

2.  Calculate  the  horse-power  of  an  engine  required  to  supply  twenty 
16  candle-power  and  five  32  candle-power  carbon  filament  lamps.  Allow 
25  per  cent,  for  losses. 

3.  What  horse-power  gasoline  engine  would  be  required  to  drive  a  5-kw. 
generator? 

4.  If  an  arc  lamp  consumes  5  amperes  at  110  volts,  calculate  its  resistance. 

5.  How  many  arc  lamps  can  be  operated  by  a  5-kw.  machine,  each  arc 
lamp  requiring  3.5  amperes  on  a  220-volt  circuit?  Allow  5  per  cent,  for 
losses. 

6.  Using  the  values  in  Table  7  calculate  a  table  giving  the  power  consumed 
by  carbon  filament  lamps  of  various  candle-power. 

7.  Which  sizes  of  rubber-covered  and  weatherproof  wire  should  be  used 
to  transmit  50  amperes?     Neglect  transmission  losses. 

8.  How  would  you  connect  six  dry  cells  to  give  greatest  voltage?  Cal- 
culate approximate  voltage  of  battery. 

9.  How  should  six  storage  batteries  be  connected  to  give  the  greatest 
voltage  and  as  large  a  current  as  possible.  Calculate  approximate  voltage 
and  current  of  battery. 

10.  When  should  the  multiple  system  of  battery  connection  be  used? 

11.  The  reading  of  an  ammeter  connected  in  series  with  a  coil  is  18 
amperes-  If  the  voltage  between  the  terminals  is  7  volts,  calculate  resist- 
ance of  coil. 


ELECTRIC  MOTORS,  DYNAMOS  AND  BATTERIES  237 

12.  Calculate  the  current  which  will  flow  through  a  resistance  of  440 
ohms,  the  voltage  between  terminal  being  110. 

13.  How  does  the  ground  detector  explained  in  this  text  work?  Explain 
its  theory  of  operation  in  detail. 

14.  Can  alternating  current  be  measured  by  direct  current  instruments? 
Give  reasons  for  your  answer. 

16.  Give  clear  abstract  of  Bulletin  No.  25  of  the  Iowa  Engineering  Ex- 
periment Station.      This  bulletin  deals  with  electricity  on  the  farm. 

16.  Name  the  various  parts  of  a  dynamo  or  motor  which  are  illustrated 
and  numbered  in  Fig,  220. 


CHAPTER  XI 
MECHANICAL  TRANSMISSION  OF  POWER 

While  the  transmission  of  power  by  electric  means  is  advanc- 
ing rapidly,  it  is  probable  that  for  some  time  to  come  power  from 
one  machine  to  another  will  be  transmitted  by  mechanical  means. 

Mechanical  transmission  of  power  between  different  machines 
may  be  accomplished  by  means  of: 

1.  Belts. 

2.  Chains. 

3.  Ropes  and  cables. 

4.  Friction  gearing. 

5.  Toothed  gearing. 

6.  Shafting. 

To  the  above  list  should  be  added  cams,  eccentrics,  connect- 
ing rods,  cranks  and  levers  as  means  for  transmitting  power  to 
the  various  parts  of  the  same  machine. 

Belts. — One  of  the  most  common  methods  of  transmitting 
power  is  by  means  of  leather,  rubber,  canvas  or  composition 
belting.  On  account  of  slipping,  the  transmission  of  power 
with  belts  is  not  positive  as  is  the  case  with  gears. 

The  simplest  arrangement  is  to  have  the  belt  connect  two  pul- 
leys, one  of  which  is  the  driver  and  the  other  is  the  driven.  The 
belt  may  be  open  or  crossed.  In  the  first  case  the  two  pulleys 
turn  in  the  same  direction.  Connecting  two  pulleys  with  a  crossed 
belt  reverses  the  direction  of  the  driven. 

The  power  transmitted  by  a  belt  depends  upon  the  adhesion 
between  the  belt  and  the  pulley.  For  indoor  work  and  under 
reasonably  dry  conditions,  leather  has  proven  to  be  the  most 
satisfactory  and  reliable  material  for  belts.  It  is,  however,  the 
most  expensive  and  its  use  cannot  be  recommended  for  outside 
work  in  inclement  weather. 

Leather  Belts. — ^Leather  belts  are  made  up  of  short  strips 
of  oak-tanned  leather,  each  strip  varying  from  44  to  60  in.  in 
length.     Before  being  tanned  for  belting  purposes  the  head,  neck, 

238 


MECHANICAL  TRANSMISSION  OF  POWER      239 

belly  and  tail  portions  of  the  hide  are  trimmed  off.  The  remain-, 
der  of  the  hide  is  divided  into  three  portions  from  which  the 
different  grades  of  belting  are  secured.  The  best  grade  of  belting 
comes  from  the  center  piece  of  the  hide,  after  a  strip  is  cut  off 
crosswise  from  the  shoulders.  The  second  grade  comes  from  the 
flanks,  and  the  poorest  grade  from  the  shoulders. 

Leather  belting  is  made  of  single  thickness,  and  is  designated 
as  single  ply,  or  single  belt.  Double-ply  belting  is  made  by  con- 
necting the  flesh  sides  of  two  thicknesses  of  leather. 

The  cost  of  double  belting  is  just  twice  that  of  single  belting, 
but  it  has  been  found  that  it  will  transmit  twice  as  much  power 
and  will  last  more  than  twice  as  long  as  single  belting.  Owing 
to  the  greater  stiffness  of  double  belting  it  will  not  conform  to  the 
surface  of  the  pulley  as  readily  as  a  single  belt,  and  its  use  is 
limited  by  the  size  of  the  pulley.  Double  belts  are  generally  not 
used  on  pulleys  less  than  10  in. 

Rubber  Belts. — These  consist  of  one  or  more  layers  of  cotton 
duck  alternating  with  layers  of  vulcanized  rubber.  The  adhesion 
of  rubber  belts  is  somewhat  better  than  that  of  leather  belts. 
Rubber  belts  will  also  stand  heat,  cold  and  moisture  better  than 
leather  belts.  The  life  of  a  rubber  belt  is  much  shorter  than  that 
of  a  leather  belt  and  the  coating  of  rubber  is  easily  ruined  by  the 
application  of  oil. 

Canvas  Belts. — Canvas  belts  are  lighter  than  rubber  belts. 
They  are  well  adapted  for  saw  mills  or  for  farm  machinery  where 
the  belt  is  exposed  to  the  weather.  Canvas  belts  stretch  and  con- 
tract with  temperature  changes  and  are  not  durable.  Painting 
improves  canvas  belts. 

Care  of  Belts. — Leather  belts  must  be  kept  clean  and  free  from 
dust,  dirt  and  oil.  Dampness  will  loosen  the  cement  which  is 
used  in  building  up  the  belt.  Some  manufacturers  have  now 
a  process  of  waterproofing  leather  belts,  but  this  has  not  been 
extensively  tried  out. 

Most  preparations  called  ''belt  dressing''  contain  rosin  and 
are  injurious  to  leather.  If  it  is  necessary  to  soften  a  leather 
belt,  neat's-foot  oil,  tallow  or  castor  oil  should  be  used. 

The  hair  side  of  a  leather  belt  should  be  run  next  to  the  pulley, 
as  this  is  the  weaker  side,  and  being  smoother  than'the  flesh  side 
the  hair  side  will  adhere  much  better  to  the  pulley. 


240 


FARM  MOTORS 


Rubber  belts  should  run  with  the  seam  side  out,  and  not  next 
to  the  pulley  .  All  animal  greases  and  oils  should  be  kept  away 
from  rubber  belts.  Boiled  linseed  oil  may  be  applied,  but  this 
should  be  done  sparingly. 

Belts  will  hold  better  when  the  pulleys  are  at  long  distances 
apart.  Two  pulleys  connected  by  a  belt  should  be  spaced  far 
enough  apart  so  as  to  allow  of  a  gentle  sag  to  the  belt  when  in 
motion.  This  distance  will  be  10  to  15  ft.  for  narrow  belts  and 
small  pulleys.  In  the  case  of  wide  belts  working  on  large  pulleys 
the  distance  between  driver  and  driven  should  be  at  least  20  ft. 
If  too  great  a  distance  is  used  the  extra  cost  of  the  belt  will  be 
wasted  and  the  extra  weight  of  the  belt  will  produce  unsteady 
motion  and  great  friction  in  the  bearings. 


Ou+sideof  Belt 


Fig.  254. 


Method  of  Lacing  Belts. — The  strength  of  the  belt  depends  not 
only  on  the  quality  of  the  material  from  which  it  is  made,  but 
also  on  the  method  used  in  connecting  the  ends.  The  ideal 
joint  is  a  cement  joint.  Such  a  joint  should  be  made  only  after 
the  ends  of  a  belt  have  been  stretched  in  position  over  pulleys. 

Lacing  made  of  rawhide  is  most  commonly  used.  Metallic 
wire  lacing  will  also  give  good  results  if  the  lace  wire  is  hammered 
below  the  surface  of  the  leather  so  as  to  prevent  excessive  wear  on 
the  lace,  and  if  care  is  taken  not  to  hay^  \y^Q  wires  cross  each  other 


MECHANICAL  TRANSMISSION  OF  POWER      241 


on  the  pulley  side  of  the  belt.  Wire  lacing  makes  a  less  clumsy 
joint  and  does  not  decrease  the  strength  of  the  belt  on  account  of 
large  holes  as  does  rawhide  lacing. 

To  cement  a  belt,  a  lap  joint  generally  equal  to  the  width  of  the 
belt  is  made  by  beveling  the  two  ends,  applying  glue  and  then 
clamping  the  two  ends  together  in  the  required  position. 

Before  a  belt  is  laced  the  two  ends  should  be  made  absolutely 
square,  otherwise  the  belt  will  tend  to  run  off  the  pulleys.  One 
method  of  lacing  a  belt  is  illustrated  in  Fig.  254. 

Other  methods  of  connecting  the 
ends  of  a  belt  are  by  means  of  belt 
fasteners,  rivets,  staples  and  sew- 
ing. These  methods  are  not 
recommended,  as  they  will  pull  out 
in  time  and  leave  the  belt  ends 
ragged. 

Pulleys. — Pulleys  are  made  of 
iron,  wood  and  paper.  Pulleys  are 
either  solid  (Fig.  255)  or  split  (Fig. 
256) .  Large  pulleys  are  usually  of 
the  split  type. 

Pulleys  designed  to  transmit 
power  by  belts  are  usually 
crowned,  that  is  the  rim  is  rounded, 
so  that  the  diameter  is  greater  at 
the  middle.  When  crowned  pul- 
leys are  used  the  belt  will  remain  at  the  center  of  the  pulley  and 
will  not  run  off.  The  width  of  the  acting  surface  or  face  of  a 
pulley  should  always  be  greater  than  that  of  the  belt. 

In  order  to  be  able  to  start  and  stop  the  driven  pulley  without 
interfering  with  the  driver,  a  combination  of  tight  and  loose 
pulleys  are  often  used.  In  this  case  one  pulley  is  fastened  to  the 
shaft  and  transmits  motion,  while  the  other  is  loose  on  the  shaft. 
The  driving  shaft  carries  a  pulley,  which  has  a  width  equal  to 
that  of  the  tight  and  loose  pulleys  put  together.  The  belt  when 
in  motion  can  be  shifted  so  that  it  will  run  over  the  tight  or  over 
the  loose  pulley,  thus  throwing  machinery  into  or  out  of  gear. 
Where  tight  and  loose  pulleys  are  employed,  or  in  any  case  where 
the  belt  may  be  shifted,  the  pulleys  are  straight,  that  is,  are  built 

16 


Fig.  255. 


242 


FARM  MOTORS 


Fig.  256. 


without  crowning,  in  order  that  the  belt  may  be  easily  moved 
from  one  pulley  to  the  other. 

The  average  leather  belt  will  not  trans- 
mit its  maximum  force  on  account  of  slip- 
ping on  the  pulleys.  The  adhesion  be- 
tween the  belt  and  pulley  can  be  increased 
by  covering  the  pulley  with  leather. 
This  method  of  increasing  the  power  trans- 
mitted should  be  used  only  in  emergencies. 
A  well-designed  drive  with  the  belts  and 
pulleys  of  proper  size  to  transmit  the  de- 
sired power  should  not  require  pulley 
covering. 

Small  pulleys  are  secured  to  the  shaft 
by  means  of  set  screws.  Large  pulleys 
are  fastened  to  the  shaft  by  keys,  or  some- 
times by  both  keys  and  set  screws. 

Stepped  pulleys  (Fig.  257)  have  several 
faces  of  different  diameters  on  both  the 
drivers  "AB"  and  driven  ''CD,"  for  vary- 
ing the  speed  of  a  shaft  by  means  of  a  shifting  belt. 

Method  of  Calculating  Sizes  of  Pulleys. — If  there  is  no  slip 
in  the  belt,  the  speeds  of  two  pulleys  connected  by  a  belt  will  vary 
inversely  as  the  diameters  of  the  pulleys. 


Fig.  257. 


MECHANICAL  TRANSMISSION  OF  POWER      243 


Calling  D  the  diameter  of  the  driver,  d  the  diameter  of  fhe' 
driven,  N  the  revolutions  of  the  driver,  and  n  the  revolutions  of 
the  driven,  the  following  equation  holds 

DN  =  dn 
(The  product  of  the  diameter  of  the  driver  and  its  revolutions 
must  be  equal  to  the  product  of  the  diameter  of  the  driven  and 
its  revolutions). 

As  an  illustration:  A  gasoline  engine  running  at  300  revolu- 
tions per  minute  has  a  belt  pulley  20  in.  in  diameter.  Calculate 
the  size  of  the  driven  pulley  if  it  is  to  run  at  600  revolutions  per 
minute. 

From  the  above  equation 

,     20X300     ^^. 

The  above  rule  applies  equally  well  to  gears,  only  the  number 
of  teeth  in  the  gears  are  used  instead  of 
the  diameters  of  the  gears.  For  example, 
if  the  driving  gear  running  at  100  revolu- 
tions per  minute  has  80  teeth,  the  driven 
must  have  40  teeth  if  it  is  to  run  at  200 


Fig.  258.  Fig.  259. 

revolutions  per  minute  and  160  teeth  if  it  is  to  run  half  as  fast 
as  the  driver. 

Quarter-turn  Belt. — Sometimes  it  becomes  necessary  to  drive 


244 


FARM  MOTORS 


by  means  of  a  belt  two  pulleys  which  are  at  or  nearly  at  right 
angles  with  each  other.  If  this  must  be  accomplished  without 
the  use  of  guide  pulleys,  as  shown  in  Fig.  258,  certain  conditions 


Fig.  260. 

are  essential.  If  A  is  the  driver,  the  follower  B  must  be  so  placed, 
that  the  belt  leaving  the  face  of  pulley  A  will  lead  to  the  center  of 
the  face  of  pulley  B  (Fig.  258) .     This  means  that  the  belt  must  be 


Fig.  261. 

delivered  from  each  pulley  in  the  plane  of  the  pulley  toward 
which  it  is  running.  If  the  direction  of  motion  of  the  driver  is 
reversed,  the  belt  will  be  thrown  from  the  pulleys. 


MECHANICAL  TRANSMISSION  OF  POWER      245 

Chain  Drives. — Chains  made  of  metal  are  used  to  some  extent 
for  transmitting  power.  The  chains  run  on  sprocket  wheels, 
which  are  provided  with  suitable  projections  (Fig.  259). 

Chain  drives  are  more  positive  than  belt  drives  and  will  operate 
in  damp  places.  The  disadvantages  of  chain  drives  are  that 
they  stretch,  are  noisy  and  are  expensive  to  keep  in  repair.  Fig. 
260  illustrates  a  chain  drive  used  in  connection  with  motors. 


o£^ 


^  Fig.  262. 

Chains  for  automobiles  are  usually  supplied  with  rollers  to 
reduce  friction. 

Rope  Transmission. — Rope  drives  offer  the  following  advan- 
tages for  power  transmission: 


Fig.  263. 


1.  Power  may  be  transmitted  to  much  greater  distances  than 
is  possible  with  belts. 

2.  Driver  and  driven  can  be  very  close  together. 

3.  Power  can  be  transmitted  more  readily  to  different  floors 
of  a  building.     This  is  advantageous  in  flour  or   cement  mills. 

4.  Shafts  of  driver  and  driven  can  be  at  any  angle  with  each 
other. 


246 


FARM  MOTORS 


5.  Drive  is  noiseless. 

6.  Loss  by  slipping  is  very  small. 

Hemp  and  cotton  ropes  are  commonly  used,  these  ropes  running 
on  cast-iron  pulleys  (Fig.  261)  which  are  provided  with  grooves 
upon  their  faces  to  keep  the  ropes  in  place.  Wire  ropes  are  used 
for  the  transmission  of  large  power  over  great  distances,  and  in 
connection  with  hoists,  elevators,  inclined  railways  and  dredging 
machinery. 

In  the  United  States  the  continuous  system  (Fig.  262)  is  most 
commonly  used.  In  this  case  ropes  are  wound  over  the  driving 
pulley  A  and  driven  pulley  B  several  times.     The  traveling  ten- 


FiG.  264. 


sion  carriage  C  keeps  the  ropes  on  the  pulleys  at  the  proper  ten- 
sion. This  system  is  especially  well  adapted  for  vertical  and 
angle  drives. 

Another  method  is  to  run  independent  ropes  side  by  side 
in  grooves  of  pulleys  (Fig.  263).  This  system  is  called  the  multi- 
ple system  and  is  used  to  some  extent  for  transmitting  large 
powers,  where  the  shafts  are  very  nearly  parallel.  The  contin- 
uous system  (Fig.  262)  has  a  much  wider  range  of  application 
than  the  multiple  system. 

Friction  Gearing. — In  the  case  of  friction  gearing  the  driver 
and  driven  are  without  teeth  and  pressed  together,  no  belts  or 
chains  being  used,  and  the  power  transmitted  is  due  to  the  fric- 


MECHANICAL  TRANSMISSION  OF  POWER      247 

tionbetween  the  surfaces  of  the  two  wheels.  In  order  to  reduce 
the  slipping  to  a  minimum  and  to  prevent  the  pressure  between 
the  two  wheels  from  being  too  great,  one  or  both  of  the  gears  are 


Fig.  265. 


Fig.  266. 


made  of  some  slightly  yielding  material  like  wood,  leather  or 
paper,  as  shown  in  Figs.  264  and  265.     If  only  one  of  the  gears  is 


248 


FARM  MOTORS 


made  of  wood  or  paper  and  the  other  of  iron,  the  gear  with  the 
softer  material  must  be  the  driver. 

Friction  gears  are  made  as  spur  gears  (Fig.  264)  if  the  axes 
to  be  connected  are  parallel.  Bevel  friction  gears  (Fig.  265)  are 
used  for  connecting  axes  at  right  angles  to  each  other. 

Another  form  of  friction  gears  consists  of  grooves  cut  in  the 
circumference  of  two  wheels,  the  projections  of  one  gear  being 
forced  into  the  grooves  of  the  other. 

The  disc  and  roller  constitute  another  form  of  friction  gearing. 
If  the  disc  revolves  at  a  uniform  speed,  the  speed  of  the  roller 
can  be  increased  by  moving  it  away  from  the  center  and  decreased 
by  moving  the  roller  toward  the  center  of  the  disc.  If  the  roller 
is  moved  past  the  center  its  motion  is  reversed. 


Fig.  267. 

The  friction  drive  as  applied  to  automobiles  (Fig.  266)  works 
on  the  principle  of  the  disc  and  roller.  A  flat-faced  disc  A  is 
attached  to  the  crank-shaft  of  the  motor.  The  other  part  con- 
sists of  a  wheel  B  keyed  to  a  shaft  S  parallel  to  the  disc  but  free 
to  move  on  the  shaft.  Speed  changes  and  reversing  can  be  accom- 
plished by  shifting  the  wheel  on  the  face  of  the  disc. 

The  clutches  explained  in  Chapter  VIII  can  also  be  called  a 
form  of  friction  gearing. 

The  objections  to  friction  gears  are: 

1.  The  drive  is  not  positive,  as  there  must  always  be  some 
slipping. 

2.  The  transmission  of  power  by  friction  gears  produces 
excessive  pressures  on  bearings. 


MECHANICAL  TRANSMISSION  OF  POWER      249 


Fig.  269. 


Fig.  270. 


Fig.  271. 


250 


FARM  MOTORS 


Friction  gears  are  used  where  the  power  to  be  transmitted  is 
not  very  great  and  where  changes  of  speed  have  to  be  made  while 
the  machinery  is  in  motion,  as  is  often  the  case  of  certain  machine 
tools. 

Toothed  Gearing. — This  form  of  power  transmission  is 
employed  when  a  positive  speed  ratio  is  desired  between  the 
driver  and  the  driven. 


Fig.  272. 

The  projections  of  one  gear  which  mesh  with  those  of  another 
are  called  teeth.  The  term  '^cogs"  is  sometimes  applied  to  teeth 
inserted  in  the  wheel  of  another  material  than  that  of  the  body  of 
the  gear. 

Gears  are  usually  made  of  cast  iron.  For  rough  work  the  gears 
are  cast,  while  for  accurate  work  cut  gears,  made  in  a  special 
machine  tool,  are  used.     Noiseless  gears  are  made  of  rawhide. 


Fig.  273. 


Fig.  274. 


compressed  between  brass  or  iron  plates.  Sometimes  one  of  the 
gears  is  provided  with  removable  wooden  teeth  to  decrease 
noise.  Rawhide  gears  must  not  be  used  in  places  where  they  may 
get  wet  and  must  not  be  lubricated.  For  most  farm  machinery 
cast-iron  gears  are  used. 

Spur  gears  (Fig.  267)  are  used  for  transmitting  power  between 
parallel  shafts.     A  combination  of  a  gear  meshing  with  teeth 


MECHANICAL  TRANSMISSION  OF  POWER      251 

cut  on  a  straight  rectangular  piece  (Fig.  268)  is  called  a  rack  and 
pinion.  An  annular  gear  (Fig.  269)  is  a  wheel  with  teeth  cut  on 
the  inside. 

Bevel  gears  (Fig.  270)  are  used  for  connecting  two  axes  which 
intersect. 

In  the  worm  and  wheel  (Fig.  271)  the  screw-like  action  of  the 
worm  A  revolves  the  wheel  B.  The  worm  and  wheel  is  used  for 
making  fine  adjustments  on  instruments.     It  is  also  employed 


Fig.  275. 

in  connection  with  hoisting  machinery,  as  by  the  proper  propor- 
tioning of  the  screw  great  weights  can  be  lifted  on  a  drum  con- 
nected on  the  same  shaft  with  the  worm  wheel.  The  worm  and 
wheel  is  also  found  on  the  steering  mechanism  of  traction  engines, 
as  illustrated  in  Chapter  VII. 

Shafting. — Shafting  is  either  employed  directly  for  transmit- 
ting power  or  is  used  in  connection  with  pulleys  and  gears. 

Shafting  is  made  of  wrought  iron  or  of  steel.  The  better  the 
material  in  the  shafting,  the  more  power  it  will  be  able  to  trans- 
mit.    Also  the  greater  the  speed  at  which  the  shaft  is  run,  the 


252 


FARM  MOTORS 


more  power  will  it  transmit.  The  torsional  strength  of  a  shaft, 
or  the  resistance  which  it  offers  to  breaking  by  twisting,  is  propor- 
tional to  the  cube  of  its  diameter. 

To  prevent  a  shaft  from  moving  endwise,  a  collar  (Fig.  272) 
is  fastened  to  the  shaft  by  means  of  set  screws. 


Fig.  276. 

To  fasten  two  lengths  of  a  shaft  end  to  end,  a  coupling  (Fig. 
273)  is  used.  To  be  able  to  fasten  or  separate  two  lengths  of 
shafting  while  they  are  revolving,  a  clutch  coupling  (Fig.  274)  or 
a  friction  clutch,  illustrated  in  another  part  of  the  book,  should 
be  used. 


Fig.  277. 


Fig.  278. 


The  standard  sizes  of  shafting  are  given  in  odd  sixteenths  of 
an  inch,  and  advance  by  eighths.  They  can  be  obtained  from 
3/16  inch  up  to  5  1/2  in.  cold-rolled.  Shafts  above  5  1/2  in. 
are  usually  turned. 


MECHANICAL  TRANSMISSION  OF  POWER      253 

Shafting  is  suspended  from  hangers  (Fig.  275)  placed  on  beams, 
floors,  or  ceilings.  A  bracket  (Fig.  276)  is  used  for  suspending 
shafting  from  walls.  Hangers  and  brackets  are  provided  with 
bearings  in  which  the  shafting  revolves.  The  collar  (Fig.  272) 
should  be  placed  on  the  shaft  against  the  bearing.  A  sufficient 
number  of  hangers  or  brackets  should  be  used  in  order  to  prevent 
the  shaft  from  bending. 

The  bearings  used  to  carry  shafting  may  be  plain  bearings,  as 
illustrated  in  connection  with  the  various  types  of  motors.  To 
reduce  the  frictional  resistance  of  a  plain  bearing,  a  roller  bearing 
or  a  ball  bearing  is  used.  In  the  roller  bearing  (Fig.  277)  the 
shaft  rolls  on  hardened  steel  roller,  while  in  the  ball  bearing  (Fig. 
278)  the  shaft  revolves  on  balls  placed  in  suitably  designed 
grooves.  Both  roller  and  ball  bearings  are  expensive  and  diffi- 
cult to  keep  in  good  order. 

In  general  the  work  which  can  be  accomplished  by  any  motor 
depends  not  only  on  the  quality  of  the  motor,  but  also  on  the 
system  used  for  transmitting  the  power  of  the  motor  to  the 
machines  where  power  is  utilized. 


INDEX 


A 

Belt  sphcing,  241 

Belts,  238 

Action  of  electricity,  200 

canvas,  239 

of  motors,  1 

leather,  238 

Adaptability  of  steam  engines,  69 

rubber,  239 

Advantages  of  rope  drive,  245 

Bituminous  coal,  22 

of  water  turbine,  179 

Boiler  furnaces,  grates  for,  ; 

Air  cooled  engine,  112 

setting,  26 

Alcohol  as  a  fuel,  103 

Boilers,  classification  of,  26 

denatured,  104 

cleaning  of,  56 

heat  value  of,  104 

internally  fired,  30 

specific  gravity  of,  104 

low  water  in,  56 

Alternating  currents,  211 

piping  for,  35 

Ammeter,  220 

rating  of,  54 

Anthracite  coal,  22 

return  tubular,  28 

Armature,  212 

vertical  fire-tube,  31 

Artificial  draft,  51 

water-tube,  33 

Automatic  governors,  77 

Boiling  point  of  water,  14 

ignition,  124 

Brake  horse-power,  7 

Automobile,  friction  drive,  248 

windmill,  192 

differential,  167 

Breast  wheel,  173 

starters,  166 

Brushes,  fitting  of,  234 

transmission,  167 

troubles,  167 

C 

Automobiles,  gasohne,  166 

steam,  165 

Calculating  size  of  pulleys,  : 

types  of,  165 

Cam,  starting,  136 

Auxiharies,  engine,  81 

Canvas  belts,  239 

B 

Balanced  valve,  62 
Batteries,  electrical,  203 

primary,  204 

storage,  206 
Battery  connections,  209 
Baume  scale,  102 
Bearings  for  shafts,  253 

hot,  9ll 

main,  80 

roller,^253 
Belt  lacing",  240 

quarter-turn,  243 


35 


Carbon  on  cylinder  walls,  139 
Carbureters  for  gasoline  engines,  105 

spray  type,  108 

surface  type,  106 
Carbureting  of  heavy  oils.  111 
Care  of  dynamos,  235 

of  motors,  235 

of  steam  engines,  88 

of  windmills,  198 
Causes  of  failure  to  start,  137 

of  motor  faihng  to  run,  138 
Cells,  dry,  205 

Edison-Lelande,  206 

Leclanche,  205 
Chain  drives,  245 


255 


256 


INDEX 


Charging  a  storage  battery,  207 

Chimneys,  51 

Churn,  131 

Circuit  breakers,  222 

Circulating  system,  forced  feed,  114 

systems,  gravity,  113 
Classes  of  water-tube  boilers,  34 
Classification  of  steam  engines,  69 

of  boilers,  26 
Coal,  kinds  of,  22 
Coil,  induction,  119 

spark,  116 
Combustion,  23  ~ 
Commercial  value  of  fuels,  24 
Commutator,  212 
Comparison  of  motors,  3 

of  cycles,  98 
Composition  of  fuels,  22 
Compound  motors,  218 
Compressed  air  starting,  135 
Condensation  losses,  70 
Condensers,  jet,  85 

surface,  85 
Condensing  engines,  70 
Conductors  of  electricity,  202 
Connecting  batteries,  209 

up  motors,-  226 
Cooling  of  gas  engines,  112 

systems,  oil,  114 
Corliss  engine,  65 

governor,  77 
Corn  sheller,  127 
Correct  mixture,  138 
Couplings  for  shafts,  252 
Cranks,  80 

Cream  separator,  130 
Crosshead,  79 
Crowning  pulleys,  241 
Current,  distribution  of,  218 
Currents,  alternating,  211 

direct,  211 
Cycle,  Diesel,  94 

four-stroke,  94 

gas-engine,  93 

two-stroke,  97 
Cycles,  comparison  of,  98 

motor,  170 


Cylinder  lubrication,  139 
water  in,  92 

D 

Denatured  alcohol,  104 
Description  of  steam  engines,  57 
Details  of  gas  tractors,  156 

of  steam  engine,  78 
Diesel  cycle,  94 
Differenital,  automobile,  167 

gear,  141 
Differentials,  150 
Direct  currents,  211 
Distillates  of  crude  petroleum,  100 
Distribution  of  current,  218 
Draft,  artificial,  51 
Drive  chains,  245 
Dry  cells,  205 
Dynamo,  210 

action  of,  210 

ignition,  121 
Dynamos,  care  of,  235 

installation  of,  233 

principal  parts  of,  212 

series,  215 

shunt,  216 


E 


Eccentric,  58,  80 
Edison-Lelande  cells,  206 
Electric  batteries,  203 

motor  on  the  farm,  226 

motors,  2,  212 

sewing  machine,  228 

washing  machine,  227 
Electricity,  action  of,  200 

conductors  of,  202 

units  of,  200 
Energy,  5 
Engine  auxiliaries,  81 

cylinder,  78 

drive,  134 

erecting,  89 

for  irrigation,  134 

foundations,  88 

four-valve,  66 


INDEX 


257 


Engine,  internal  combustion,  93 

knocks  in,  90 

starting,  89 

stopping,  of  90 
Engines,  condensing,  70 

Corliss,  65 

non-condensing,  70 

rating  of,  134 
Ensilage  cutter,  127 
Equal  cut-off,  67 

lead,  67 
Equivalent  of  evaporation,  55 
Erecting  an  engine,  89 

windmills,  195 
Essential  parts  of  a  gas  engine,  104 
Evaporation,  equivalent  of,  55 
Events  of  stroke,  60 
Exhaust  lap,  60 

pipe  heads,  84 

piping,  135 

smoke  in,  139 


Failure  of  motor  to  run,  causes  of, 
138 

to  start,  causes  of,  137 
Farm  Hght-plant,  228 
Feed  pumps,  44.  144 
Feed-water  heater,  49 
Field,  magnetic,  212 
Firing,  systems  of,  52 
Fining  fuel  tanks,  164 
Fitting  brushes,  234 
Fixing  a  traction  engine  for  winter, 

165 
Flash  point  of  kerosene,  101 
Float-feed  carbureters,  109 
Force,  4 

Forced  feed  circulating  system,  114 
Foundations  for  engines,  88 

of  gas  engines,  134 
Four-stroke  cycle,  94 
Four-valve  engine,  66 
Friction  drive,  167 

for  automobile,  248 

gearing,  246 
17 


Fuel,  alcohol,  103 

tank,  location  of,  134 

tanks,  filling  of,  164 
Fuels,  16 

commercial  value  of,  24 

composition  of,  22 

for  gas  tractors,  156 

gas  engine,  99 
Fundamental  parts  of  traction  en- 
gines, 140 
Fuses,  222 


G 


Gage,  43 

Gages,  steam,  42 

Gas  engine,  air  cooled,  112 

cooling  of,  112 

cycle,  93 

essential  parts  of,  104 

foundation,  134 

fuels,  99 

hopper  cooled,  112 

installation,  134 

operation  of,  138 

pounding  in,  139 

selection,  132 

starting,  135 

water  cooled,  112 
engines,  classification  of,  94 

governing  of,  125 
natural,  23 
producer,  100 
traction  engines,  155 
tractor,  plowing  with,  163 

reversing  gear  for,  162 

uses  of,  163 
tractors,  details  of,  156 

fuels  for,  156 
Gasoline,  100 

automobiles,  166 
engine  on  the  farm,  126 
engines,  carbureters  for,  105 
Gear,  differential,  141 
Gearing,  friction,  246 
toothed,  250 
of  windmill,  190 


258 


INDEX 


Governing  of  gas  engines,  125 

hit-or-miss,  125 

by  varying  quality  of  mixture, 
126 
quantity  of  mixture,  126 
Governor,  throttling,  75 

of  windmill,  189 
Governors,  automatic,  77 
Governors,  Corliss,  77 

steam  engine,  73 
Grates  for  boiler  furnaces,  35 
Gravity  circulating  system,  113 

specific,  12 
Ground  detector,  222 


Indicated  horse-power,  6 

Indicator  cards,  steam  engine,  69 

Induction  coil,  119 

Injectors,  44 

Installation  of  dynamos,  233 

of  gas  engines,  134 

of  motors,  233 

of  steam  engines,  88 
Internal  combustion  engine,  93 
Internally  fired  boilers,  30 
J 

Jet  condensers,  85 
Jump-spark  system,  1 18  . 


K 


Hangers  for  shafts,  253 
Hay  press,  127 
Heads,  exhaust  pipe,  84 
Heat,  8 

mechanical  equivalent  of,  11 

units  of,  10 

value  of  alcohol,  104 
Heaters,  feed  water,  49 
Heavy  oils,  101 

carbureting  of.  111 
High  tension  magneto,  123 
Hit-or-miss  governing,  125 
Hopper  cooled  gas  engine,  112 
Horse-power,  6 
Hot  air  engine,  2 

bearing,  91 
Hydraulic  ram,  179 

principle  of,  180 


Ignition,  automatic,  124 
dynamo,  121 
jump  spark,  118 
make-and-break,  116 
premature,  139 
systems,  116 

Impulse  turbine,  87 
\  water  motors,  175 


Kerosene,  flash  point  of,  101 
Knock;s  in  engine,  90 


Lap,  exhaust,  60 

steam,  60 
Lead,  61 

equal,  67 
Leakage  losses,  73 
Leather  belts,  238 
Leclanche  cells,  205 
Light  plant  for  farm,  228 
Lignite,  22 

Location  of  fuel  tank,  134 
Losses,  condensation,  70 

in  steam  engines,  70 

leakage,  73 

mechanical,  72 

radiation,  72 
Low  tension  magneto,  123 

water  in  boilers,  56 
Lubrication  of  cylinder,  139 

of  windmills,  198 
Lubricators,  81 

M 

Magnetic  field,  212 
Magneto,  low  tension,  123 


INDEX 


259 


Magnetos,  123 
Main  bearing,  80 
Make-and-break  system,  116 
Management  of  boilers,  55 

of  traction  engines,  164 
Matter,  4 
Mechanical  equivalent  of  heat,  1 1 

losses,  72 

stokers,  54 
Mechanism,  reversing,  140 
Meters,  electric,  219 
Mixer  valve,  108 

Mixture  of  fuel  for  gas  engines,  138 
Motion,  4 
Motor  cycles,  170 
Motors,  care  of,  235 

comparison  of  types,  218 

compound,  218 

connecting  of,  226 

electric,  212 

for  traction  engines,  140 

installation  of,  233 

principal  parts  of,  212 

series,  215 

sewing  machine,  178 

shunt  wound,  216 

starting  and  stopping  of,  234 

water,  171 


N 


Natural  gas,  23 
Non-condensing  engines,  70 


Parts  to  examine  before  starting  an 

engine,  135 
Pelton  wheel,  177 
Petroleum,  23 

distillates  of,  100 
Pipe  fittings,  37 
Piping,  exhaust,  135 

for  boilers,  35 
Piston,  78 

valve,  63 
Plain  slide  valve,  59 
Plowing  with  a  gas  tractor,  163 
Plug,  spark,  121 
Pop  safety  valves,  41 
Pounding  in  gas  engine,  139 
Power  of  stream,  172 

of  windmills,  198 

plants,  steam,  25 

transmission  of,  238 

windmill,  191 
Premature  ignition,  139 
Pressure,  5 

Primary  batteries,  204 
Principal  parts  of  dynamos,  212 

of  motors,  212 

of  windmills,  186 
Producer  gas,  100 
Properties  of  saturated  steam,  16 
PuUeys,  241 

calculating  size  of,  242 

crowning  of,  241 
Pumping  outfit,  129 
Pumps,  feed,  44,  144 


Oil  cooling  system,  114 

engine,  2 

water  in,  139 

pump,  83 
Oils,  heavy,  101 

specific  gravity  of,  102 

weight  per  gallon,  102 
Ohm's  law,  201 

Operating  traction  engines,  164 
Operation  of  gas  engine,  138 
Overshot  wheel,  173 


Q 

Quarter-turn  belt,  243 

R 

Radiation  losses,  72 

Ram,  hydrauhc,  179 

Rating  of  boilers,  54 

of  gasoline  engines,  134 
of  storage  batteries,  208 
of  traction  engines,  163 


260 


INDEX 


Remedies  for   automobile   troubles, 

167 
Return  tubular  boilers,  28 
Reversing  gear  for  gas  tractor,  162 

mechanism,  140 
Rheostat,  223 
Roller  bearings,  253 
Rope  drive,  245 

advantages  of,  245 
Rubber  belts,  239 
Rudder  of  windmill,  187 


S 


Safety  valves,  40 
Saturated  steam,  15 
Sawing  outfit,  129 
Semi-anthracite  coal,  22 
Semi-bituminous  coal,  22 
Selection  of   a  gas  engine,  132 
Separators,  steam,  83 
Series  dynamos,  215 

motors,  215 
Setting  valves,  66 
Sewing  machine,  electric,  228 

motor,  178 
Shaft  bearings,  253 

couplings,  252 

hangers,  253 
Shafting,  251 

sizes  of,  252 
Shunt  dynamos,  216 

motors,  216 
Sizes  of  shafting,  252 
Sliding  gear  transmission,  167 
Solar  motor,  2 
Sources  of  energy,  1 
Smoke  in  exhaust,  139 
Spark  arrester,  145 

coil,  116 

plug,  121 
Specific  gravity,  12 

of  alcohol,  104 
of  oils,  102 

heat,  11 
Spray  carbureters,  108 
Spraying  outfit,  129 


Starters  for  automobiles,  166 
Starting  and  stopping  dynamos,  235 
motors,  234 

an  engine,  89 

by  compressed  air,  135 

cam,  136 

a  gas  engine,  135 

an  oil  engine,  101 
Steam  automobiles,  165 

engine  governors,  73 
description  of,  57 
details,  78 
indicator  cards,  69 

engines,  adaptability  of,  69 
care  of,  88 
classification  of,  69 
installation  of,  88 
losses  in,  70 
Steam  gages,  42 

generation  of,  14 

lap,  60 

power  plants,  25 

properties  of  saturated,  16 

saturated,   15 

separators,  83 

superheated,  15 

traction  engines,  141 

traps,  43 

turbines,  85 

wet,  15 
Steel  towers,  192 
Stokers,  mechanical,  54 
Stopping  an  engine,  137 
Storage  batteries,  206 

charging  of,  207 

rating  of,  208 

testing  of,  208 
Straw  burner,  142 
Stroke,  events  of,  60 
Superheated  steam,  15 
Surface  carbureters,  106 

condensers,  85 
Switches,  223 
Systems  of  firing,  52 


Temperature,  9 


INDEX 


261 


Testing  of  storage  batteries,  208 
Theory  of  steam  generation,  14 
Thermometers,  9 
Threshing  with  a  gas  tractor,  170 
Throtthng  governor,  75 
Toothed  gearing,  250  ' 

Towers,  steel,  192 

windmill,  192 

wood,  192 
Traction  engine  motors,  140 

engines,  140 
gas,  155 

management  of,  164 
operation  of,  165 
steam,  141 
uses  of,  163 
valve  gears  for,  146 
Transmission,  friction,  167 

of  power,  238 
Transmissions  for  automobiles,  167 
Traps,  steam,  43 
Troubles  of  automobiles,  167 
Turbines,  impulse,  87 

steam,  85 

water,  177 
Two-stroke  cycle,  97 
Types  of  automobiles,  165 

of  motors  compared,  218 

of  valve  gears,  62 

of  water  motors,  173 

of  windmills,  184 


U 


Undershot  wheel,  173 
Units  of  electricity,  200 

of  heat,  10 
Uses  of  gas  tractor,  163 

of  traction  engines,  163 
of  windmills,  199 


Valve,  balanced,  62 

gears  for  traction  engines,  146 

types  of,  62 
mixer,  108 
piston,  63 


Valve,  plain  shde,  59 

setting,  66 
Valves,  39 

pop  safety,  41 

safety,  40 
Varying  quaUty  of  mixture,  126 

quantity  of  mixture,  126 
Vertical  fire-tube  boilers,  31 
Voltmeter,  219 

W 

Washing  machine,  131 

electric,  227 
Water  column,  43 

cooled  gas  engine,  112 

glass,  43 

in  cylinder,  92 

in  oil  engine,  139 

motors,  171  * 

impulse,  175 
types  of,  173 

tube  boilers,  33 

turbine,  advantages  of,  179 

turbines,  177 
Waterwheels,    overshot,    undershot, 

breast,  173 
Wattmeter,  220 
Weight  of  oils  per  gallon,  102 
Wet  steam,  15 
Windmill,  brake,  192 

gearing,  190 

governor,  189 

power,  191 

principal  parts  of,  185 

rudder  of,  187 

towers,  192 
Windmills,  care  of,  198 

erecting  of,  195 

lubrication  of,  198 

power  of,  198 

types  of,  184 

uses  of,  199 
Wind  wheel,  185 
Wood  towers,  192 
Work,  5 
Worm  and  wheel,  251 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED   BELOW 


RENEWED  BOOKS  ARE  SUBJECT  TO  IMMEDIATE 
RECALL 


LIBRARY,  UNIVERSITY  OF  CALIFORNIA,  DAVIS 

Book  Slip-50m-12,'64(F772s4)458 


365458 

TJ712 
Potter,  A. A.  P6 

Farm  motors. 


LIBRARY 

UNIVERSITY  OF  CALIFORNIA 

DAVIS 


